Probing FeSi, a d -electron topological Kondo insulator candidate, with magnetic field, pressure, and microwaves
[2];
[4];
[1];
- Department of Physics, University of California San Diego, La Jolla, CA 92093
- Center for High Pressure Science and Technology Advanced Research, Pudong, Shanghai 201203, People’s Republic of China
- Center for High Pressure Science and Technology Advanced Research, Pudong, Shanghai 201203, People’s Republic of China, Univ Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, Villeurbanne 69100, France
- State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200433, People’s Republic of China, Shanghai Research Center for Quantum Sciences, Shanghai 201315, People’s Republic of China
- Los Alamos National Laboratory, Los Alamos, NM 87545
- University of California Irvine, Irvine, CA 92967
Recently, evidence for a conducting surface state (CSS) below 19 K was reported for the correlated d -electron small gap semiconductor FeSi. In the work reported herein, the CSS and the bulk phase of FeSi were probed via electrical resistivity ρ measurements as a function of temperature T , magnetic field B to 60 T, and pressure P to 7.6 GPa, and by means of a magnetic field-modulated microwave spectroscopy (MFMMS) technique. The properties of FeSi were also compared with those of the Kondo insulator SmB 6 to address the question of whether FeSi is a d -electron analogue of an f -electron Kondo insulator and, in addition, a “topological Kondo insulator” (TKI). The overall behavior of the magnetoresistance of FeSi at temperatures above and below the onset temperature T S = 19 K of the CSS is similar to that of SmB 6 . The two energy gaps, inferred from the ρ( T ) data in the semiconducting regime, increase with pressure up to about 7 GPa, followed by a drop which coincides with a sharp suppression of T S . Several studies of ρ( T ) under pressure on SmB 6 reveal behavior similar to that of FeSi in which the two energy gaps vanish at a critical pressure near the pressure at which T S vanishes, although the energy gaps in SmB 6 initially decrease with pressure, whereas in FeSi they increase with pressure. The MFMMS measurements showed a sharp feature at T S ≈ 19 K for FeSi, which could be due to ferromagnetic ordering of the CSS. However, no such feature was observed at T S ≈ 4.5 K for SmB 6 .
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF); USDOE Laboratory Directed Research and Development (LDRD) Program; Shanghai Municipal Science and Technology; State of Florida
- Grant/Contract Number:
- FG02-04-ER46105; DOE BES program "Science in 100 T"; DE FG02-87-ER45332; 89233218CNA000001; FG02-87-ER45332; DMR-1810310; 2019SHZDZX01; 20ZR1405300; DMR-1157490/1644779
- OSTI ID:
- 1924839
- Alternate ID(s):
- OSTI ID: 1974938
- Report Number(s):
- LA-UR-22-21765; e2216367120
- Journal Information:
- Proceedings of the National Academy of Sciences of the United States of America, Journal Name: Proceedings of the National Academy of Sciences of the United States of America Vol. 120 Journal Issue: 8; ISSN 0027-8424
- Publisher:
- Proceedings of the National Academy of SciencesCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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