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

Abstract

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.

Authors:

Fang, Yuankan ^[1]; Ran, Sheng ^[2]; Xie, Weiwei ^[3]; Wang, Shen ^[4]; Meng, Ying Shirley ^[4]; Maple, M. Brian ^[5]

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+ Show Author Affiliations

1. Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA 92093,, Center for Advanced Nanoscience, University of California, San Diego, La Jolla, CA 92093,
2. Department of Physics, University of California, San Diego, La Jolla, CA 92093,
3. Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803,
4. Department of NanoEngineering, University of California, San Diego, La Jolla, CA 92093
5. Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA 92093,, Center for Advanced Nanoscience, University of California, San Diego, La Jolla, CA 92093,, Department of Physics, University of California, San Diego, La Jolla, CA 92093,

Publication Date:

2018-08-06

Research Org.:

Univ. of California, San Diego, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE National Nuclear Security Administration (NNSA), Office of Defense Nuclear Security

OSTI Identifier:

1463065

Alternate Identifier(s):

OSTI ID: 1540301

Grant/Contract Number:  

DEFG02-04-ER46105; NA0002909; FG02-04ER46105

Resource Type:

Published Article

Journal Name:

Proceedings of the National Academy of Sciences of the United States of America

Additional Journal Information:

Journal Name: Proceedings of the National Academy of Sciences of the United States of America Journal Volume: 115 Journal Issue: 34; Journal ID: ISSN 0027-8424

Publisher:

Proceedings of the National Academy of Sciences

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE