Diamond Light Source is the UK’s national synchrotron science facility. By accelerating electrons to near light-speed, Diamond generates brilliant beams of light from infra-red to X-rays which are used for academic and industry research and development across a range of scientific disciplines including structural biology, physics, chemistry, materials science, engineering, earth and environmental sciences.
Topological objects are localized in space and exist for extended periods of time. In magnets, there are many examples of such objects such as domain walls, skyrmions and antiskyrmions, and recently, many more have been predicted to exist, including hopfions, a 3D analogue of the skyrmionic vortex, as well as torons, merons and blochions. Noncollinear magnetic systems offer a rich spectrum of excitations across a huge range of timescales, some tied to the dynamics of ordered magnetic lattices and some to the internal dynamics of the magnetic textures themselves. Further, the 3D modulations present in such objects lead to emergent electric and magnetic fields acting on spin-polarised electrons and magnons, resulting in unusual transport phenomena.
Until now, conventional ferromagnetic resonance (FMR) has been used extensively to determine fundamental magnetic parameters in thin films using resonance frequencies (related to internal and applied fields) and relaxation (determined by damping of the resonance). Further, it has been used as an indirect identification of the internal dynamic skyrmion modes, e.g., clockwise and anticlockwise gyration modes or breathing modes. However, topological magnetic systems require the development of new techniques that give direct access to their dynamical properties. The novel technique of X-ray detected FMR (XFMR) enables us to study the element-selective magnetization dynamics via X-ray magnetic circular dichroism (XMCD). Time-dependent XFMR measures both the amplitude and phase of the spin precession of chemically distinct layers. The experimental challenge is that the precession frequency is on the order of GHz and the precession cone angle is <1°. The solution lies in stroboscopic measurements utilizing the time structure of the synchrotron (∼500 MHz). The radio frequency (RF) field that drives the spin precession is synchronized with the X-ray pulses using the clock of the synchrotron. Each X-ray pulse measures the magnetisation cone at precisely the same point in the cycle. In brief, XFMR combines FMR and XMCD as pump and probe, respectively.
The inverse spin-Hall effect (ISHE) is a process that converts a spin current into an electric current and can be investigated systematically in simple ferromagnetic/paramagnetic bilayer systems, whereby the spin pumping driven by ferromagnetic resonance injects a spin current into the paramagnetic layer. We aim to combine XFMR with ISHE, which detect the AC and DC components of the spin pumping, respectively, giving insight into the effects of emergent fields on the transport properties of topological magnetic objects.
The student will be making use of the following research techniques:
Sample growth: Magnetron sputtering in Oxford.
Ex-situ characterization (SQUID, XRD/XRR, MOKE) at Diamond Light Source (DLS) and Oxford.
Photolithography at Oxford.
ISHE measurements at Oxford and the Magnetic Spectroscopy Lab at DLS.
XFMR and XAS/XMCD/XMLD: X-ray spectroscopies at DLS beamlines (and others).
FMR measurements in the Magnetic Spectroscopy Lab at DLS.
The student will obtain the following training:
Graduate courses, transferrable skills training at Oxford.
Hesjedal group: Practical training in magnetron sputtering and MBE, structural and magnetic sample characterisation; photolithography; transport (ISHE).
van der Laan team, DLS: Experimental synchrotron techniques (XAS, XMCD, XMLD), XFMR, as well as FMR and ISHE. Theoretical modelling and micromagnetic simulations.
Funding for the studentship has been applied for through the Diamond Doctoral Studentship Programme (funding decision early December 2022). Fully funded studentships will be available for UK/Home fee students only.
Diamond Light Source Ltd holds an Athena SWAN Bronze Award, demonstrating their commitment to provide equal opportunities and to advance the representation of women in STEM/M subjects: science, technology, engineering, mathematics and medicine.
Diamond jointly funds around 15-20 studentships every year with a variety of collaborators from both academic institutions to industry partners. Students accepted onto these projects will be part of our yearly cohort intake and are supported by both their academic and Diamond supervisors, as well as a dedicated Student Engagement team based at Diamond.
Diamond studentships are typically 50% funded by Diamond and 50% by the partnering university institution (or 25% funded by Diamond if there is a third party collaborator). Students are therefore required to spend 50% of their studentship at Diamond, with most students relocating to the local area for this period. Support on suggested accomodation options are provided by Diamond.
Benefits of Diamond's jointly funded studentships
If you have further questions please contact the Student Engagement team on firstname.lastname@example.org.
Further guidance for students can be found here as well as more information about life at Diamond found here.
Applications are now closed.
Diamond Light Source is the UK's national synchrotron science facility, located at the Harwell Science and Innovation Campus in Oxfordshire.
Copyright © 2022 Diamond Light Source
Diamond Light Source Ltd
Harwell Science & Innovation Campus
Diamond Light Source® and the Diamond logo are registered trademarks of Diamond Light Source Ltd
Registered in England and Wales at Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, United Kingdom. Company number: 4375679. VAT number: 287 461 957. Economic Operators Registration and Identification (EORI) number: GB287461957003.