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Title: Evidence for a conducting surface ground state in high-quality single crystalline FeSi

Journal Article · · Proceedings of the National Academy of Sciences of the United States of America
 [1];  [1];  [2];  [1];  [1];  [1]
  1. Univ. of California, San Diego, CA (United States)
  2. Louisiana State Univ., Baton Rouge, LA (United States)

We report anomalous physical properties of high-quality single-crystalline FeSi over a wide temperature range of 1.8–400 K. The electrical resistivity ρ(T) can be described by activated behavior with an energy gap Δ = 57 meV between 150 and 67 K, below which the estimated energy gap is significantly smaller. The magneto-resistivity and Hall coefficient change sign in the vicinity of 67 K, suggesting a change of dominant charge carriers. At ~19 K, ρ(T) undergoes a cross-over from semiconducting to metallic behavior which is very robust against external magnetic fields. The low-temperature metallic conductivity depends strongly on the width/thickness of the sample. In addition, no indication of a bulk-phase transition or onset of magnetic order is found down to 2 K from specific heat and magnetic susceptibility measurements. The measurements are consistent with one another and point to complex electronic transport behavior that apparently involves a conducting surface state in FeSi at low temperatures, suggesting the possibility that FeSi is a 3D topological insulator.

Research Organization:
Univ. of California, San Diego, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE National Nuclear Security Administration (NNSA), Office of Defense Nuclear Security
Grant/Contract Number:
FG02-04ER46105; NA0002909; DEFG02-04-ER46105
OSTI ID:
1463065
Alternate ID(s):
OSTI ID: 1540301
Journal Information:
Proceedings of the National Academy of Sciences of the United States of America, Vol. 115, Issue 34; ISSN 0027-8424
Publisher:
National Academy of Sciences, Washington, DC (United States)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 17 works
Citation information provided by
Web of Science

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