Secondments

All MagnEFi Early Stage Researchers will spend time on secondment at a second host institute within the consortium.  Some of the originally planned secondments have been delayed due to the Covid19 pandemic, but once the secondments have been completed, a brief summary will be posted here.

ESR8 Adrien Petrillo: TU/e ->University of Salamanca, department of Applied Physics, Salamanca, Spain
Duration:  20/11/2022 to 26/11/2022 
Main goal: Learn about implementation of anisotropy and DMI changes on propagating spin waves in MUMAX3

This secondment was set in order for Adrien to learn and improve his skills on mumax3 simulations. The goal was to develop simulations on the propagation of Damon-Eshbach and Forward volume more in 20nm Co layer, where the surface anisotropy was locally modified. The aim of this project was to improve our understanding of the behavior of spin waves once they travel to a region where the surface anisotropy is locally modified and understand better the physic intrinsic to our experimental data

ESR10 Mouad Fattouhi: USAL -> Spin-Ion Technologies
Duration:  28/11/2022 to 07/01/2023
Main goal: Carry out large scale micromagnetic simulations to study the DW creep regime dynamics in edge irradiated samples.

For this secondment, Mouad took the responsibility to simulate DW creep dynamics in samples exposed to different irradiation doses at their borders. He found interesting results for the films with the highest irradiation rate, however for the cases he concluded that and optimized version of the simulation code is needed to describe accurately the underlying physics. Currently he is working more on the optimization of his code and keeping the collaboration with Spin-Ion researchers. 

ESR 6 Adithya Rajan JGU -> USAL
Duration: 14.11.2022 – 22.11.2022
Main Goal: Atomistic simulation of spin texture dynamics of a non collinear antiferromagnet

During this secondment, Adithya performed atomistic simulations of magnetic field sweeps in various directions of the Kagome plane of a non collinear antiferromagnet with the aim to study the unconventional features in the field sweep loop like plateaus, bumps and kinks. The information of spin structures from the atomistic simulations and also of the physical parameters like the anomalous Hall conductivity and the scalar spin chirality would help understand these unconventional features in the field sweep. 

ESR10 Mouad Fattouhi: USAL->C2N, UPSaclay
Duration:  4 weeks (17/10/2022 to 27/11/2022)
Main goal: Carry out Kerr microscopy measurement to measure field driven DW dynamics in presence of in-plane strain.

In this secondment, Mouad carried out Kerr microscopy measurements for magnetic/piezoelectric devices fabricated by C2N-UPsaclay group and measured the DW dynamics in the presence of in-plane strain. With the PI Dr.Liza Herrera-Diez and ESR Subhajit Roy they found interesting results where one can maximize the effect of mechanical strain on magnetic DWs by applying small voltages in the piezoelectric substrate.  Mouad later measured a new device and carried out data analysis to generate graphs.    

ESR 7 Beatrice Bednarz: JGU -> UPSaclay
Duration: 2 weeks (31/10/2022 – 04/11/2022 and 14/11/2022 – 18/11/2022)
Main goal: Finalize the experiments started in M26, M31 and M32

In this third secondment in Paris, Beatrice finalized the experiments which she had started during the first two secondments. During the previous one, she had successfully shown the reversible magneto-ionic control of the anisotropy in an exchange biased system. However, controlling the exchange bias while keeping the anisotropy fixed, could not be shown so far. To answer whether this is also possible, Beatrice performed gating experiments on samples with different PtMn thicknesses on top of ferromagnetic Co. She found that not enough ions can be moved through metallic PtMn layers to manipulate the exchange bias, even if it was only 2 nm thin. However, the resistivity of the PtMn could be modified by the gating, which opens a new possibility for manipulation of the PtMn with ionic liquid gating.

ESR 5 Md Golam Hafiz: Leeds -> UPSaclay
Duration: 2 Weeks (19th Oct 2022-30th Oct 2022)
Goal: Ionic liquid gating experiments on magnetic thin film with structural inversion asymmetry

During this secondment at the University of Paris Saclay, Golam learned the ionic liquid gating technique. Transport measurement was carried out on ultra-thin Ta/Pt/CoB/Ir/Pt films. The technique is non-volatile and highly energy efficient. Thus, magnetization significantly changes with ±2 V.

ESR 6 Adithya Rajan JGU -> Sensitec
Duration: 18.10.2022 – 21.10.2022 and 31.10.2022- 05.11.2022
Main goal: Learn about mechanical strain generation  and measurement techniques

During this secondment, Adithya learnt how to measure the strain generated in a substrate  using a commercial strain gauge by measuring the change in the resistance of metallic wires in the strain gauge. 

Additionally, commercial ceramic piezoactuators were obtained to integrate to a thin film sample grown on any substrate and apply piezostrain by applying appropriate electric field across the piezoactuator. 

This system will be used to study the effects of strain in the antiferromagnetic domains of NiO and CoO which are known to be highly sensitive strain in their crystal structure.

ESR1 Subhajit Roy: UPSaclay ->INRIM
Duration: 2 weeks (19/09/2022 – 30/09/2022)
Main goal: Analysis of the OOP strain driven domain wall creep dynamics

ESR1 Subhajit Roy analyzed the non-volatile OOP strain driven domain wall motion in the creep regime experimental data using Python. Based on daily discussions with Adriano di Pietro and Prof. Gianfranco Durin, Subhajit was able to analyzed strain driven domain wall motion in the creep regime. The pinning of the domain wall motion in the creep regime after applying the voltage has been analyzed with the 1D model which agreed well with the experimental results. This secondment was really helpful in learning about the physics of strain-driven domain wall motion in the creep regime.

ESR1 Subhajit Roy: UPSaclay ->USAL
Duration: 2 weeks (05/09/2022 – 16/09/2022)
Main goal: Simulation of the OOP strain driven domain wall dynamics

ESR1 Subhajit Roy studied the OOP non-volatile strain effect on domain wall motion using Mumax3. In a close collaboration with Prof. Luis Lopez Diaz’s help and suggestions, Subhajit was able to simulate strain driven domain wall dynamics that matches well with experimental data. Domain wall motion was accelerated in the presence of OOP strain in particular, the depinning and flow regime. This secondment was incredibly beneficial in understanding the mechanics of strain-driven domain wall motion.

ESR 5 Md Golam Hafiz: Leeds -> INRIM
Duration: 3.5 Weeks (15th Sept 2022-8th Oct 2022)
Goal: Modelling the effect of E-Field on a thin film with structural inversion asymmetry by DFT calculation

During this secondment, Golam used the FLEUR package to understand the basics of density function theory and basic simulation. He also learned to perform structural relations and optimization of relevant parameters. Now he is working in collaboration with Adriano di Pietro (ESR 3) to understand the effect of e-field on magnetic anisotropy and DMI of Pt/CoB/Ir films. The results from the simulation will be published with experimental results.

ESR 15 Giovanni Masciocchi: Sensitec GmbH –> Technical University of Eindhoven (TU/e)
Duration: 3 weeks (13th  Aug. – 3rd  Sept. 2022)
Main goal: Investigation of strain on synthetic ferrimagnets

During his stay at the Technical university of Eindhoven (TU/e) ESR 15 (Giovanni Masciocchi) investigated the effects of strain on synthetic ferrimagnet multilayers (Co/Gd). After the realization of different samples, the influence of strain on the magnetic properties (e.g. magnetic compensation and anisotropy) of those systems was explored. By quantifying the magnetostriction of these types of structures with different numbers of layers and interfaces, we aim to get a better understanding of this material system for spintronics.

ESR 3 Adriano di Pietro: INRIM ->Tu/e
Duration 2 weeks: 1st – 12th August 2022
Main goal: Theoretical support of electric field interactions with spin waves

During his stay at the Tu/e, Adriano collaborated with Adrien Petrillo and prof. Lavrijsen developing a scattering model to try and explain experimental data regarding the spin wave propagation under the effect of the electric field. This toy model shows that the influence of the Dzyaloshinskii-Moriya interaction on Demon-Heshbach modes transmission and reflection is negligible when compared to the effect of surface anisotropy. Adriano and Adrien also worked on fitting the inductance data from the spin wave experimental setup in the Tu/e lab: by analyzing the model they were able to determine that the spin wave antenna modeling needs to be improved to account for the appearance of secondary peaks in the frequency generation.

ESR 3 Adriano di Pietro: INRIM ->Salamanca
Duration 3 weeks: 4th – 23rd July 2022
Main goal: Micromagnetic modelling  and contributions of electric field to magnetic domain structures

During his stay at USAL, Adriano worked with Prof. Lopez-Diaz and Prof. Garcia-Sanchez on a modification to the MumḾax3 Micromagnetic code that enabled it to account for a micromagnetic DMI tensor found in the low symmetry S4 systems. The modification involved 2 steps:

  • As a first step he had to calculate the boundary conditions and effective field generated by this new type of interaction.
  • As a second step he modified the source code and wrote the results from the analytical calculation in a discretized form.

The new version of the code was validated by successfully predicting the dependency of Antiskyrmion radius on the material parameters.  

ESR 6 Adithya Rajan JGU -> USAL
Duration: 21.06.2022 – 02.07.2022
Main Goal: Atomistic simulation of spin texture dynamics of a non collinear antiferromagnet

Having already developed an atomistic model that simulates the magnetic properties like the antiferromagnetic transition temperature and the magnetization response to a magnetic field out of the Kagome plane, Adithya started to simulate the spin dynamics of the system in response to a magnetic field in the Kagome plane. With this, the information such as the anomalous Hall conductivity at each direction of magnetic field were obtained to compare with the experimental results. 

ESR 4 Jintao Shuai: Leeds ->USAL
Duration: 3 weeks (20/06 – 09/07/2022)
Main goal: Simulation of the surface acoustic wave effect on domain wall motion in the creep regime

ESR4 Jintao Shuai studied the surface acoustic wave (SAW) effect on domain wall motion in creep regime using Mumax. With Prof Luis Lopez Diaz’s help, Jintao was able to simulate domain wall motion within the creep regime. Domain wall motion was accelerated in the presence of both standing and travelling SAWs agreeing with Jintao’s experimental results. This secondment was extremely helpful to understand the mechanism of the SAW-assisted domain wall motion.

ESR 14 Mandy Syskaki: Singulus -> UPSaclay
Duration: 4 weeks (20/06/2022-15/07/2022)
Main goal: Ionic liquid gating experiments on perpendicular magnetized synthetic antiferromagnet thin film material stack

Following the previous experiments conducted in the first secondment period in University Paris Saclay, the use of the ionic liquid gating technique on the synthetic antiferromagnet thin film stack shows large and reproducible effects. Therefore, more experiments on the dedicated set-ups were performed to study the magneto-ionic effects on the properties of the samples. Preliminary results show that a sample with low RKKY coupling demonstrates an increase in the effective magnetization, due to a decrease of the magnetically dead layer of the top ferromagnet and a large modification of the RKKY field.

ESR 7 Beatrice Bednarz: JGU -> Aalto
Duration: 2 weeks (30/05/2022 – 11/06/2022)
Main goal: Investigate gating with Li-ions

During this secondment at Aalto university Beatrice investigated the effect of lithium-ion gating on antiferromagnetic PtMn. Li-gates were grown and patterned on different samples for which the behavior from oxygen-ion gating was already known. In this way, it was possible to compare the two methods and learn about the advantages of each. An extensive study of the effect of the gating on the magnetic properties as well as the IV-loops was performed. This will help to get a better understanding of the effect of gating on antiferromagnetic materials.

ESR 6 Adithya Rajan JGU -> USAL
Duration: 16.05.2022 – 04.06.2022
Main Goal: Atomistic simulation of spin texture dynamics of a non collinear antiferromagnet

Adithya did his first secondment at the University of Salamanca (SPAIN) in the Department of Applied Physics.

During this period, he joined the “Sinamags” research group and worked on a project focused on understanding the effect of magnetic field on the dynamics of spin structure in a non collinear antiferromagnet by means of atomistic simulation of the system under the supervision of Dr. Rocio Yanes Diaz and Prof. Luis Lopez Diaz.

During this period an atomistic model of the experimental system was built to replicate the physical and magnetic properties. 

ESR8 Adrien Petrillo: TU/e ->Spin-Ion Technologies, Paris-Saclay, C2N, France
Duration: 15/05/2022 to 26/05/2022
Main goal: Interface engineering by He+ irradiation and ionic gating

During this secondment, Adrien collaborated with Spin-Ion technologies in order to locally irradiate Ta(4nm)/Pt(3nm)/Co(20nm)/MgO(55nm) nanostrips. The goal was to locally modify the surface anisotropy, analogous to a change of anisotropy induced by an electric field. By doing so, we expected to have a system with local change of anisotropy that we could relate to the one used in E-field change of magnetic anisotropy, which would help us in the interpretation of our data

ESR 13 Gyan van der Jagt: Spin-Ion Technologies -> Institut Néel, CNRS
Duration: 1 week (9-5-2022 – 13-5-2022)
Main goal: measuring domain wall motion in irradiated films at large magnetic fields

Gyan performed high magnetic field Kerr microscopy to measure magnetic field driven domain wall motion in various irradiated samples. Under the supervision of dr. Stefania Pizzini and with the help of ESR 12 Cristina Balan, Gyan learned about the use of microcoils and high-speed pulse generators to apply ultra-short high magnetic field pulses to measure domain wall motion. With the results of this study, Gyan hopes to shed more light on the influence of disorder and irradiation on domain wall motion in the flow regime.

ESR 7 Beatrice Bednarz: JGU -> UPSaclay
Duration: 4 weeks (21/04/2022 – 13/05/2022)
Main goal: Continue the measurements started in M26 with optimized samples

In the second part of her project, Beatrice investigated the influence of ionic liquid gating on the exchange coupling. She brought a variety of samples to Paris to find out which system works best for the ionic liquid gating. In this way, she investigated different ferromagnetic materials, the influence of the growth order and the effect of the annealing. All samples were analyzed by anomalous Hall effect measurements. As a result of the secondment, Beatrice found a stack in which the magnetic anisotropy could be reversibly controlled by the ionic liquid gating while showing exchange coupling to the antiferromagnet. This stack will be further optimized now to achieve tunable control of the exchange coupling.

ESR 15 Giovanni Masciocchi: Sensitec ->USAL
Duration: 1 month (20.03.2022 to 25.04.2022)
Main goal: Micromagnetic modelling of vortex domain walls with nonuniform strain

Giovanni did his first secondment at the University of Salamanca (SPAIN) in the Department of Applied Physics.

During this period, he joined the “Sinamags” research group and  worked on a project focused on understanding the effect of localized strain on the dynamics of vortex domain walls by means of micromagnetic simulations under the supervision of Prof. Eduardo Martinez and Prof. Luis Lopez Diaz.

The results obtained will support the understanding of the behavior of domain walls in magnetic sensors and will be used together with extensive experimental investigations.

ESR 14 Mandy Syskaki: Singulus -> UPSaclay
Duration: 4 weeks (14/02/2022-11/03/2022)
Main goal: Ionic liquid gating experiments on perpendicular magnetized synthetic antiferromagnet thin film material stack

Mandy learned how to use the ionic liquid gating technique during her secondment in UPSaclay. Gating experiments were performed on a thin film synthetic antiferromagnet material stack with perpendicular magnetic anisotropy, using the polar mode of the Kerr microscope, to observe changes in the magnetic domains of the system and the room temperature Hall effect experimental set-up, to measure the magnetic hysteresis loops through the anomalous Hall effect. Non-volatile changes on the switching fields and the remnant states of the system were observed due to magneto-ionic interactions.

ESR12 Cristina Balan: Institut Néel -> Spin-Ion
Duration: 3 weeks, February 2022
Main goal: Interface engineering with He+ irradiation

Cristina completed her 3 week secondment at the start-up Spin-Ion Technologies in February 2022, under the supervision of Dr. Dafiné Ravelosona and ESR 13 Gyan van der Jagt. Together they studied the effect of He+ irradiation on the dynamics in creep and flow regime of chiral domain walls in Pt/Co/AlOx trilayers. During her secondment, Cristina learned about the precise control of inter-atomic displacements, ultra-fast He+ ion beam facility and how this technology can be used to control micromagnetic parameters in a ultra-thin ferromagnetic system, such as magnetic anisotropy, magnetization and Dzyaloshinskii-Moriya Interaction.

ESR10 Mouad Fattouhi: USAL->Senitec
Duration: 4 weeks (13/02-11/03/22)
Main goal: Learn about the clean roam processes for fabricating magneto resistive multiturn sensors.

This secondment was planned for Mouad to learn how the magnetoresistive multiturn sensors are fabricated and characterized inside the cleanroom of Sensitec. Mouad was involved in the R&D activities of the company. He assisted the full process of the sensor fabrication and carried out hysteresis measurements of the papered wafers. Moreover, Mouad contributed to the modelling part of the sensor properties using mechanical and micromagnetic simulations.   

ESR 7 Beatrice Bednarz: JGU -> Sensitec
Duration: 3 weeks (14/02/2022 – 04/03/2022)
Main goal: Learn about magnetic sensor development and investigate the influence of annealing on PtMn films

During this secondment, Beatrice followed a production process at Sensitec. She learned about the industrial process of magnetic sensor development, as well as the product development, from the initial contact of the customer and Sensitec until the final product. Very insightful was the different weight that is given to different aspects of sensor preparation in an industry. While exact reproducibility of effects, functioning under harsh conditions, low failure rate, and lifetime exceeding tens of years are hardly investigated in the academic environment, they play an essential role in sensor development for the automotive industry and at Sensitec the corresponding testing is standard routine. With respect to the science progress within MagnEFi, Beatrice developed her exchange coupled samples further and learned from the experience of Sensitec with exchange coupling and the advantages and drawbacks of using IrMn or PtMn as the antiferromagnetic material. 

ESR 14 Mandy Syskaki: Singulus ->JGU
Duration: 2 weeks (17-28/01/22)
Main goal: To learn about X-ray reflectivity and SQUID magnetometry

During the second part of the secondment in University of Mainz, utilising the previously acquired knowledge on X-ray reflectometry and SQUID magnetometry, a series of thin film material stacks grown by magnetron sputtering with the Singulus ROTARIS sputtering tool were measured. The X-ray reflectometry gave useful insight for the smoothness of the layers, so that the optimum deposition conditions are established. The measurements with the SQUID magnetometer at lower temperatures allowed the calculation of the compensation ratio and the magnetic anisotropy of the material stacks, which is of critical importance for the interpretation of the results, obtained from the ionic-liquid-gating experiments.

ESR 4 Jintao Shuai: University of Leeds -> Evico + IFW Dresden
Duration: 3 weeks (23/02 – 11/03/2022)
Main goal: Observation of domain evolution in Pt/Co/Ir thin films via Kerr microscopy

ESR4 Jintao Shuai completed his secondment at Evico in collaboration with Professor Schaefer’s group at IFW Dresden. Jintao Shuai observed domain evolution of the Pt/Co/X (X = Ta, Pt, Ir, and Ru) multilayer thin films via Kerr Microscopy under the supervision of Prof Rudolf Schaefer and the help from Dr Ivan Soldatov. In addition, thin films were also characterised by Magnetic Force Microscopy (MFM) at zero magnetic field to understand magnetisation states without an external field. The results provided valuable information for further optimisation of the thin films to obtain skyrmions.

ESR13 Gyan van der Jagt: Spin-Ion -> USAL
Duration: 1 week remotely + 3 weeks (29/11/2021 – 17/12/2021) (4 weeks total)
Main Goals: 1. Simulation of magnetic domain wall motion in samples with varying crystalline disorder profiles created with He+irradiation. 2. Simulation of magnetic domain wall motion in wires with modulated disorder from the edges.

Gyan performed micromagnetic simulations on the field driven motion of magnetic domain walls in samples with different crystalline microstructures using the Mumax3 program. Under the supervision of Prof. Luis López Días, he performed an extensive set of characterizations regarding the interplay between the dispersion of magnetic properties along crystalline grains and the size of the grains, and their effect on the domain wall velocity at large fields. This knowledge was then used to compare simulated domain wall motion in three different films with varying microscopic structures with experimental data. The experimental data on the domain wall velocity as well as the micromagnetic parameters was obtained at Spin-Ion Technologies. From the results of the first project, he was able to confirm that the observed experimental changes in domain wall velocity were indeed influenced by different microscopic structures.

Gyan also initiated a second set of simulations, regarding domain wall motion in magnetic wires with disorder coming from the edges, and its modulation by ion irradiations. The initial simulations serve as a jumping off point for future micromagnetic simulations when more experimental data becomes available.

ESR 7 Beatrice Bednarz: JGU -> UPSaclay
Duration: 1 week (01/11/2021 – 05/11/2021)
Main goal: Learn how the ionic gating setup works and check the size of the effect on three types of samples

Beatrice conducted her first secondment at the Université Paris-Saclay under the guidance of Liza Herrera Diez. With the help of ESR 2 Rohit Pachat she successfully learned how to gate samples with ionic liquids. She investigated three types of samples: a ferromagnetic sample, a synthetic antiferromagnet and a natural antiferromagnet. The goal was to check how large the influence of the gating on the anisotropy is for the three types of samples. For this purpose, she used the Kerr microscope and the anomalous Hall effect setup to measure the hysteresis loops and image the domain patterns of the samples. The ferromagnetic and synthetic antiferromagnet samples showed a very strong effect of the gating. The antiferromagnetic sample didn’t show an effect yet. These results will be used for further sample optimization. Follow-up experiments will take place in 2022.

ESR 11 – Sreeveni Mozhikunnath Das, Aalto University, Finland -> INRIM, Turin
Duration 4 weeks (Sep 25 – Oct 25, 2021)
Main goal: Learn and perform DFT calculations for theoretical understanding of iDMI and magnetic anisotropy.

ESR 11 Sreeveni Mozhikunnath Das completed her first secondment at INRIM Turin from Sep 25 to Oct 25, 2021. The ESR is currently optimizing MgO/CoFeB/Ta heterostructure for hosting stable skyrmions. Hence the use of first principle calculations of MgO/CoFeB/Ta heterostructure will provide a theoretical understanding of the dzyaloshinskii-moriya interaction (DMI) and perpendicular magnetic anisotropy (PMA) contribution by various interfaces. She learned the basics of density functional theory and performed basic simulations including the design of super cells, structural relaxation and optimization of relevant parameters using the FLEUR package. Following the secondment, she will continue with DFT calculations and will perform magnetic force theorem calculations with spin orbit coupling for the estimation of magnetic anisotropy and DMI. Furthermore, the simulation results will be compared with experimental observations. 

ESR12 Cristina Balan: Institut Néel, CNRS -> USAL
Duration: 3 weeks (20/09/2021 – 15/10/2021) + 1 week remotely
Main goalSimulation of magnetic Domain Wall (DW) dynamics in non-centrosymmetric multilayer thin films with perpendicular magnetic anisotropy (PMA). 

Description:
Cristina completed, under the supervision of Prof Luis Lopez-Diaz, her first secondment at the University of Salamanca to simulate the motion of chiral Néel DW driven by an out-of-plane  magnetic field  in thin films stabilized by Dzyaloshinskii-Moriya interaction (DMI) . 
Using mumax3 program, micromagnetic simulations were carried out to reproduce the DW velocities, previously measured experimentally from bubble expansion in continuous thin films, to study in particular the regime above the Walker field, where the velocity is maintained high, without breakdown, in systems with large DMI. The magnetic parameters  implemented in the calculation (Ms, Keff, D) were measured at the Institut Néel.  The simulations were realised initially in the case of a perfect system with no disorder or temperature; later, different sized grains were introduced with different anisotropy distributions values to study the effects on the velocity of the DWs in the low field regime. 
Using these simulation results as reference, Cristina will carry out micromagnetic simulations to reproduce the DW velocities  measured in a similar magnetic system, but obtained after a voltage gate was applied for several minutes on  micro capacitor– like devices. This set of simulations are more challenging to realise, as the magnetic parameters were locally modified with electric field and only few of them could be measured, but of much interest as they can give a better understanding of how  magnetic DWs  can be efficiently used  in future spintronic applications.

ESR 1 Subhajit Roy: UPSaclay ->USAL
Duration: 2 weeks (05/07/2021 – 15/07/2021)
Main goal: Simulation of strain induced magnetic Domain Wall (DW) motion in thin film heterostructures 

Description:
ESR1 Subhajit Roy conducted his first secondment at the University of Salamanca to model the magnetic Domain Wall (DW) movement in thin films under the presence of strain using Mumax3. Due to Covid-19 travel restrictions, the first part of the secondment took place virtually. Over the duration of the secondment Subhajit had access to the University of Salamanca cluster remotely to perform simulations and at that time several methods, including online meetings and emails, were used for communication and discussion. From this short online secondment Subhajit learnt how to perform Magnetic DW movement simulation using Mumax3. Moreover, he also successfully simulated Field driven and Strain driven Magnetic DW movement under the supervision of Prof Luis Lopez-Diaz. In summary, Subhajit studied the influence of strain on the magnetic domain wall motion using Mumax3. The results show that strain is a significant tool for efficient manipulation of domain walls and could be used in further spintronic devices and applications. 

ESR 2 Rohit Pachat: Université Paris-Saclay -> Institut Néel, CNRS
Duration: 2 weeks (05/07/2021 – 16/07/2021)
Main Goal: Domain wall velocity (in the flow regime) and Asymmetric bubble expansion

Description:
ESR 2 Rohit Pachat conducted his first secondment at Institut Néel, CNRS to obtain domain wall (DW) velocity and effective DMI field (HDMI) in W/CoFeB/HfO2 thin films using MOKE under the supervision of Dr. Stefania Pizzini. Rohit studied the effect of different annealing conditions on the DW velocity and HDMI and correlated them. In addition, he also studied the same properties after the application of Electric field. The results obtained show that the influence of annealing parameters on magnetic properties is significant and optimizing the parameters for tuning magnetic properties is of great importance.

ESR3 Adriano di Pietro: INRIM -> UPSaclay
Duration: 4 weeks (07/06/2021 – 07/07/2021) 
Main goal: Collaboration with ESR2 on electrical fields

During his visit in at C2N in Paris, Adriano investigated the effect of annealing conditions and electric field treatment on DMI strength and domain wall velocity in HfO2/CoFeB/W multi-layers fabricated by Rohit Pachat. The results obtained by MOKE measurements seem to suggest that both these parameters have huge effects on the the aforementioned physical quantities and the application of an electric field was confirmed to be an effective method for increasing the domain wall velocity in the creep regime. Different annealing processes also have an important impact on the magnetic properties of the samples they alter the structural properties of magnetic interfaces at a very deep level. Further theoretical studies have to be carried out in order to outline how the degree of crystallinity of these interfaces can alter the magnetic properties of the samples. 

The measurements were not conclusive in showing that the E-field has a decisive impact on the tenability of DMI in these samples: the changes in said physical quantity were present but not large. These measurements sparked the interest to discover the mechanism giving rise to this particular behavior and helped in creating a template for future ab-initio simulations back in Turin, as well as providing further need for the secondment of Rohit Pachat to carry out measurements on more specialized equipment in the Institut Nèel (Grenoble).

ESR 4 Jintao Shuai: Leeds ->USAL
Duration: 8 weeks (08/04 – 02/06/2021)
Main goal: Simulation of thin films under surface acoustic waves

Description:
ESR4 Jintao Shuai conducted his first secondment at the University of Salamanca to model the magnetic behaviour of the thin films under surface acoustic waves (SAWs) using Mumax3. Due to Covid-19 travel restrictions, the secondment took place virtually. Various methods, including online meetings and emails, were used during the secondment to ensure the quality of the secondment. Account access to the University of Salamanca cluster was created to guarantee Jintao access to the necessary resources to perform simulations. Jintao Shuai successfully simulated standing and travelling SAWs under the supervision of Prof Luis Lopez-Diaz and Dr Eduardo Martinez. Jintao studied the influence of the SAW properties on the domain wall motion. The results show that surface acoustic waves-assisted domain wall motion is promising for efficiently manipulating domain walls, which is also beneficial to understanding the physics behind the phenomenon.

ESR 14 Mandy Syskaki: Singulus ->JGU
Duration: 2 weeks (5-18/10/2020)
Main goal: To learn about X-ray reflectivity and SQUID magnetometry

Under the guidance of Professor Gerhard Jakob, multi-layered material stacks were deposited with the Singulus ROTARIS sputtering tool, so the thickness and roughness of the layers could be investigated by X-ray reflectometry using the four circle Bruker D8 Discover thin film-diffractometer. For the fitting of the obtained data, I learned to use the relevant software, i.e. Gen-X and Leptos. This gave me new insight into how to determine and optimize the quality of the films by tuning deposition parameters, such as pressure and power.

The second goal of my secondment was to learn how to use the MPMS XL SQUID magnetometer by Quantum Designs, which will allow me to investigate the magnetic properties of material stacks at lower temperatures. The magnetic moment of the different systems was measured as a function of the applied field at different temperatures. 

ESR9 Pingzhi Li: TU/e -> Smart Photonics
Duration: 5 weeks (08/10/20-20/11/20)
Main goal: To explore photonics circuit integration of magnetic nanostructures for circuit guided all-optical switching

Description:
Pingzhi completed his first secondment as a visiting researcher at “Smart Photonics”, which is a world leading fab producing chips based on integrated photonic circuits based on InP platform. There he became acquainted with the R&D and production of the cutting-edge integrated photonic system. During his stay, he made efforts to seek opportunities to bring the spintronic material into the standard photonic circuitry from the company in the hopes of extending the functionalities of both the integrated photonics and state-of-the-art spintronics through stack and circuit design. With obtained expertise as well as the connection with the company’s management and research teams, he aims to do further research into hybrid integration of spintronics into photonics.