Topological metals and semimetals
Electronic topological materials are crystalline solids which host novel fermionic quasiparticles that typically have no counterpart in high energy physics. Examples are topological insulators, and Dirac and Weyl semimetals. They are being intensively studied for their exotic quantum states and associated physical characteristics which have potential applications.
Current projects
This project is being undertaken in collaboration with Dr Jian-Rui Soh, of the École Polytechnique Fédérale de Lausanne (EPFL), Switzerland, and scientists at the ISIS Neutron and Muon Source, the Diamond Light Source, the Institut Laue–Langevin, and the Petra-III X-ray Facility. This work was initiated with support from the Oxford Quantum Materials Platform Grant (EPSRC grant no. EP/M020517/1).
This activity is being undertaken in collaboration with Prof. Yanfeng Guo, of ShanghaiTech University, China. The work is supported by the ShanghaiTech–Oxford Collaboration Project
Prof. Andrew Boothroyd
Clarendon Laboratory
Oxford, OX1 3PU
United Kingdom
phone
+44 (0) 1865 272376
fax
+44 (0) 1865 272400
Recent results
Discovery of an ideal Weyl semimetal.
Weyl semimetals exhibit exceptional electronic transport due to the presence of topological band crossings called Weyl nodes.
The nodes come in pairs with opposite chirality, but their number and location in momentum space is otherwise material-specific.
Together with colleagues in the Rudolf Peierls Centre for Theoretical Physics, Oxford, and a team of international collaborators,
we have found that the layered intermetallic EuCd2As2 in a magnetic field is what Bernevig has termed the hydrogen atom of a Weyl semimetal,
i.e. one with a single pair of Weyl nodes at the Fermi level and without overlapping electron bands.
The discovery opens the door to exploration of a wide range of exotic physics predicted for Weyl fermions in the solid state.
The results are reported in
Ideal Weyl semimetal induced by magnetic exchange
J.-R. Soh, F. de Juan, M. G. Vergniory, N. B. M. Schröter, M. C. Rahn, D. Y. Yan, J. Jiang, M. Bristow, P. Reiss, J. N. Blandy, Y. F. Guo, Y. G. Shi, T. K. Kim, A. McCollam, S. H. Simon Y. Chen, A. I. Coldea, and A. T. Boothroyd
Phys. Rev. B 100 (2019) 201102(R) (arXiv:1901.10022)
See also:
Coupling of magnetic order and charge transport in the candidate Dirac semimetal EuCd2As2
M. C. Rahn, J.-R. Soh, S. Francoual, L. S. I. Veiga, J. Strempfer, J. Mardegan, D. Y. Yan, Y. F. Guo, Y. G. Shi, and A. T. Boothroyd
Phys. Rev. B 97 (2018) 214422 (arXiv:1803.07061)
J.-R. Soh, E. Schierle, D. Y. Yan, H. Su, D. Prabhakaran, E. Weschke, Y. F. Guo, Y. G. Shi, and A. T. Boothroyd
Phys. Rev. B 102 (2020) 014408 (arXiv:2005.04952 )
Facilities and Equipment in the Group
The group has access to a range of state-of-the art equipment for sample
preparation, characterisation and fundamental measurements.