The interaction between magnetism and electronic band structure topology in magnetic topological semimetals remains unclear, which has been conceived as the source for rich unconventional bulk transport properties, as well as anomalous surface or edge states. It also allows for magnetic control of different magnetic topological phases such as axion insulators, Weyl semimetals, and quantum anomalous Hall insulators. These exotic topological phases have been expected to play important roles in next-generation low energy consumption electronic and spintronic devices.
Recently, China's Steady High Magnetic Field Facility (SHMFF) under Hefei Institutes of Physical Science (HFIPS), Chinese Academy of Sciences (CAS) supported users to prove magnetism-induced topological transition in a magnetic topological phase EuAs3.
Combining magnetotransport measurements, angle-resolved photoemission spectroscopy (ARPES), and first principles calculations, the team, consisting of professors from Fudan University, ShanghaiTech University, and HFIPS, demonstrated both the magnetic ordering and external magnetic field can induce topological transition in a new magnetic semimetal EuAs3 with a monoclinic structure.
The band structure calculations and magnetotransport measurements of the antiferromagnetic (AFM) ground state at low temperature demonstrates that EuAs3 is a magnetic topological massive Dirac metal, featuring a pair of massive Dirac points, inverted bands and topological surface states on the (010) surface.
Shubnikov-de Haas (SdH) oscillations and band structure calculations in the external magnetic field driven spin-polarized state suggested a topological nodal line semimetal nature with an extremely large magnetoresistance.
The ARPES measurements in the paramagnetic state verified the topological nodal line structure at the Y point in the Brillouin zone as predicted by band calculations.
In this research, the SdH quantum oscillations measured in SHMFF provided important evidence for demonstrating the topological nodal line structure in the spin-polarized state of EuAs3.
"The new magnetic semimetal EuAs3 will provide a rich platform to explore exotic physics arising from the interaction of magnetism with topology," said Prof. GUO Yanfeng from ShanghaiTech University.
Their findings have been published on Nature Communications.
SHMFF, which is located on science island of Hefei City, has been put into trial operation and commissioned for user service since 2008. It is a wide range of user facilities and services for multi-disciplinary and cross-disciplinary researches under steady high magnetic fields, that span condensed matter, electron strong correlation, topological insulator, nano-material fabrication, chemical reaction, neurosciences, biochemistry, pharmacology, biomedical sciences and more.
Calculated topological nodal-line structure (a) – (b) without and (c) with spin-orbit coupling (SOC) in the spin-polarized state of EuAs3 (Image by SHI Xianbiao)
The SdH quantum oscillations measured in Steady High Magnetic Field Laboratory of HFIPS (Image by CHENG Erjian)