Abstract
Determining the electronic phase diagram of a quantum material as a function of temperature (T) and applied magnetic field (H) forms the basis for understanding the microscopic origin of transport properties, such as the anomalous Hall effect (AHE) and topological Hall effect (THE). For many magnetic quantum materials, including EuAl4, a THE arises from a topologically protected magnetic skyrmion lattice with a nonzero scalar spin chirality. We identified a square skyrmion lattice (sSkL) peak in Eu(Ga1-xAlx)4 (x=0.9) identical to the peak previously observed in EuAl4 by performing neutron-scattering measurements throughout the phase diagram. Comparing these neutron results with transport measurements, we found that in both compounds the maximal THE does not correspond to the sSkL area. Instead of the maximal THE, the maximal magnetocaloric-effect boundaries better identify the sSkL lattice phase observed by neutron-scattering measurements. The maximal THE therefore arises from interactions of itinerant electrons with frustrated spin fluctuations in a topologically trivial magnetic state.
| Original language | English |
|---|---|
| Article number | 165136 |
| Journal | Physical Review B |
| Volume | 111 |
| Issue number | 16 |
| DOIs | |
| State | Published - Apr 15 2025 |
Funding
The neutron-scattering and materials-synthesis work is supported by the U.S. Department of Energy (DOE), Basic Energy Sciences (BES), under Grant No. DE-SC0012311 and by the Robert A. Welch Foundation under Grant No.C-1839, respectively (P.D.). K.J.N. is in part supported by the U.S. Department of Energy, Office of Science, Office of Workforce Development for Teachers and Scientists, Office of Science Graduate Student Research (SCGSR) program. The SCGSR program is administered by the Oak Ridge Institute for Science and Education for the DOE under Contract No. DE\u2010SC0014664. K.J.A. and E.M. have been supported by the Robert A. Welch Foundation under Grant No.C-2114 and J.M.M. was partially supported by the NSF Grant No. NSF DMR 1903741. A major portion of this research used resources at the High Flux Isotope Reactor and Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. The beam time was allocated to Corelli on Proposal No. IPTS-27961, HB1A on Proposal No. IPTS-30611.1, and GP-SANS on Proposal No. IPTS-28145.