Abstract
Topological Hall effect (THE) is a hallmark of scalar spin chirality, which is found in static skyrmion lattices. Recent theoretical works have shown that scalar spin chirality could also emerge dynamically from thermal spin fluctuations. Evidence of such a mechanism was found in the kagome magnet YMn6Sn6 where fluctuations arise from frustrated exchange interactions between Mn kagome layers. In YMn6Sn6, the rare-earth ion Y3+ is nonmagnetic. When it is replaced by a magnetic ion (Gd3+-Ho3+), the intrinsically antiferromagnetic Mn-Mn interlayer coupling is overwhelmed by the indirect ferromagnetic Mn-R-Mn one, relieving frustration. This generates interesting anomalous Hall conductivity, but not THE. Here we show that Er lies in an intermediate regime where direct and indirect interactions closely compete, so that ErMn6Sn6 can switch from one regime to the other by temperature, i.e., from a collinear ferrimagnetic ground state to a spiral antiferromagnet at 78 K. The antiferromagenetic phase forms a dome in the temperature-field phase diagram. Close to the boundary of this dome, we find a sizable fluctuations-driven THE, thus underscoring the universality of this chiral fluctuation mechanism for generating nonzero scalar spin chirality.
| Original language | English |
|---|---|
| Article number | 094411 |
| Journal | Physical Review Materials |
| Volume | 8 |
| Issue number | 9 |
| DOIs | |
| State | Published - Sep 2024 |
Funding
The authors thank M. Newburger and M. Page for insightful discussions, and O. Remcho, X. Yao, and T. Hogan for assistance with the experiments. The work at Boston College was supported by the National Science Foundation under Award No. DMR-2203512. This material is based upon work supported by the Air Force Office of Scientific Research under Award No. FA2386-21-1-4059 and No. FA9550-23-1-0124. The work at Howard University was supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences under Award No. DE-SC0022216. This research at Howard University used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 using NERSC Award No. BES-ERCAP0023852 and Accelerate ACCESS PHY220127. I.I.M. acknowledges support from the National Science Foundation under Award No. DMR-2403804. Our neutron scattering experiments were performed at the Swiss Spallation Neutron Source SINQ, Paul Scherrer Institut, Switzerland, and the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory, USA. P.B. acknowledges SNSF Projects No. 200021-188707 and No. 200020-182536 for financial support.