Abstract
Weyl electrons are intensely studied due to novel charge transport phenomena such as chiral anomaly, Fermi arcs, and photogalvanic effect. Recent theoretical works suggest that Weyl electrons can also participate in magnetic interactions, and the Weyl-mediated indirect exchange coupling between local moments is proposed as a new mechanism to induce spiral magnetic ordering by involving chiral Weyl electrons. Here, we present evidence of Weyl-mediated spiral magnetism in SmAlSi from neutron diffraction, transport, and thermodynamic data. We show that the spiral order in SmAlSi results from the nesting between topologically nontrivial Fermi pockets and weak magnetocrystalline anisotropy, unlike related materials (Ce,Pr,Nd)AlSi, where a strong anisotropy prevents the spins from freely rotating. We map the magnetic phase diagram of SmAlSi and reveal an A phase where topological magnetic excitations may exist. Within the A phase, we find a large topological Hall effect whose variation with the magnetic field direction suggests a dominant helical instead of cycloidal character, as theoretically predicted for the Weyl-induced spiral order.
| Original language | English |
|---|---|
| Article number | 011035 |
| Journal | Physical Review X |
| Volume | 13 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 2023 |
Funding
F. T. and P. N. thank I. Mazin for helpful discussions. This material is based upon work supported by the Air Force Office of Scientific Research (AFOSR) under Grant No. FA2386-21-1-4059. The authors thank D. Haskel, P. Ryan, L. Rijos-Carretero, W. Koll, and J. A. Gupta for helpful discussions. S.-M. H. is supported by the MOST-AFOSR Taiwan program on Topological and Nanostructured Materials, Grant No. 110-2124-M-110-002-MY3. A portion of this research used resources at the High Flux Isotope Reactor, a DOE Office of Science User Facility operated by Oak Ridge National Laboratory. Any mention of commercial products is intended solely for fully detailing experiments; it does not imply recommendation or endorsement by NIST. A portion of this work was performed at the National High Magnetic Field Laboratory, which is supported by the National Science Foundation Cooperative Agreement No. DMR-1644779 and the state of Florida. P. N. acknowledges support from the Institute for Quantum Matter, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Grant No. DE-SC0019331. The work at Northeastern University was supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences Grant No. DE-SC0022216 and benefited from Northeastern University’s Advanced Scientific Computation Center and the Discovery Cluster and the National Energy Research Scientific Computing Center through DOE Grant No. DE-AC02-05CH11231. The work at TIFR Mumbai was supported by the Department of Atomic Energy of the Government of India under Project No. 12-R&D-TFR-5.10-0100. The work at Temple University was funded by the National Science Foundation under Grant No. NSF/DMR-1945222. R. Z. and J. S. acknowledge the support of the U.S. Office of Naval Research (ONR) Grant No. N00014-22-1-2673.
| Funders | Funder number |
|---|---|
| MOST-AFOSR | 110-2124-M-110-002-MY3 |
| National Science Foundation | DMR-1644779 |
| Office of Naval Research | N00014-22-1-2673 |
| U.S. Department of Energy | DE-SC0022216 |
| Air Force Office of Scientific Research | FA2386-21-1-4059 |
| Office of Science | |
| Basic Energy Sciences | DE-SC0019331 |
| Northeastern University | |
| National Energy Research Scientific Computing Center | DE-AC02-05CH11231 |
| Tata Institute of Fundamental Research | |
| Department of Atomic Energy, Government of India | 12-R&D-TFR-5.10-0100, NSF/DMR-1945222 |