Abstract
Recent reports of colossal negative magnetoresistance (CMR) in a few magnetic semimetals and semiconductors have attracted attention because these materials are devoid of the conventional mechanisms of CMR such as mixed valence, double-exchange interaction, and Jahn-Teller distortion. New mechanisms have thus been proposed, including topological band structure, ferromagnetic clusters, orbital currents, and charge ordering. The CMR in these compounds has been reported in two forms: either a resistivity peak or a resistivity upturn suppressed by a magnetic field. Here we reveal both types of CMR in a single antiferromagnetic semiconductor Eu5In2As6. Using the transport and thermodynamic measurements, we demonstrate that the peak-type CMR is likely due to the percolation of magnetic polarons with increasing magnetic field, while the upturn-type CMR is proposed to result from the melting of a charge order under the magnetic field. We argue that similar mechanisms operate in other compounds, offering a unifying framework to understand CMR in seemingly different materials.
| Original language | English |
|---|---|
| Article number | 115114 |
| Journal | Physical Review B |
| Volume | 111 |
| Issue number | 11 |
| DOIs | |
| State | Published - Mar 15 2025 |
Funding
The work at Boston College was funded by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Physical Behavior of Materials under award number DE-SC0023124. This material is based upon work supported by the Air Force Office of Scientific Research under Awards No. FA2386-21-1-4059 and No. FA9550-23-1-0124. A.R. acknowledges support from the Swedish Research Council, Grant No. 2021-04360. 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. The support for neutron scattering was provided by the Center for High-Resolution Neutron Scattering, a partnership between the National Institute of Standards and Technology and the National Science Foundation under Agreement No. DMR-2010792. The identification of any commercial product or trade name does not imply endorsement or recommendation by the National Institute of Standards and Technology. A portion of this research used resources at the High Flux Isotope Reactor, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. The beam time was allocated to VERITAS on Proposal No. IPTS-31509. Part of this work is based on experiments carried out at the Swiss Muon Source , Paul Scherrer Institute, Villigen, Switzerland. We thank E. Kenney for assistance with the data analysis.