Monday and Tuesday this week saw the 2018 UK Magnetism meeting organised by the IOP. It was great to see many familiar faces and some excellent talks and posters. There was a plenary talk given by Albert Fert and the Wohlfarth lecture given by my former supervisor, Prof Gino Hrkac. There was also the AGM for the IOP Magnetism group and I am very happy to have been elected as an ordinary member of the group, thanks to all who voted for me, I look forward to getting more involved in the IOP. I am looking forward to the next magnetism conference!
Today sees the publication of my latest article, published in Scientific Reports. This work involves the use of first principles methods and atomistic spin dynamics to study the magnetic properties of Fe/Ir/Fe sandwiches. Such magnetic systems with interfaces are extremely difficult to model accurately, but by using first and second principles models we have been able to obtain layer-by-layer equilibrium and dynamic properties, which are even trickier to determine experimentally.
By using the SIESTA code to structurally relax the interfaces (see schematic) of different Ir, the ground state atomic structure can be found. We then used the Budapest SKKR code to determine an extended Heisenberg Hamiltonian. This complex Hamiltonian has a complete lack of translational invariance perpendicular to the plane, essentially meaning that each Iron plane is in its own environment which interact differently with the others. Our spin dynamics results show that this has important consequences for the equilibrium magnetic properties, as well as the dynamics. We find that the spinwaves are stiffened with increasing temperature, which goes against the thermal effects that usually result in a decrease. This is due to the frustration arising from the exchange at the interface with Ir. Finally, our results reveal a plane-wise dependence of the demagnetisation process.
The work was done in collaboration with international groups including ICN2 (Barcelona), Budapest University of Technology and the Universities of Exeter and York. The work is Open Access meaning that it is free for all to view (see this link). This was made possible due to the Sheffield Hallam University Open Access Fund. I would also like to thank Eddy Verbaan and the Library Research Support Team for their help in obtaining funding to make this article Open Access.
The Materials and Engineering Research Institute (MERI) at Sheffield Hallam University is funding 2 Graduate Teaching Assistant PhD studentships on any topic in materials and engineering, physics and mathematics. This is a competitive process, whereby applications from students are made with the support of an academic at Sheffield Hallam. A short proposal of the work during the PhD is required and can be done in collaboration with the academic. Potential projects in the areas of computational magnetism are:
- Ultrafast spin dynamics in systems with emergent phenomena – involving a multiscale approach, combining first and second principles modeling.
- Low energy control of magnetism in complex magnetic materials – using a range of approaches to simulate the dynamics of advanced functional materials to find new materials and routes towards low energy devices.
Potential projects are not limited to those described above. If you have a specific project in mind or if you require more information on these potential projects, please get in touch by email.
The deadline for applications is 1st Febrary 2018, see this link for more details on the application process and eligibility criteria.