Title: Imaging emergent heavy Dirac fermions of a topological Kondo insulator

Abstract

The interplay between strong electron interactions and band topology is a new frontier in the search for exotic quantum phases. The Kondo insulator SmB₆ has emerged as a promising platform because its correlation-driven bulk gap is predicted to host topological surface modes entangled with f electrons, spawning heavy Dirac fermions. Unlike the conventional surface states of non-interacting topological insulators, heavy Dirac fermions are expected to harbour spontaneously generated quantum anomalous Hall states, non-Abelian quantum statistics, fractionalization and topological order. Yet, the small energy scales required to probe heavy Dirac fermions have complicated their experimental realization. Here we use high-energy-resolution spectroscopic imaging in real and momentum space on SmB₆. On cooling below 35 K, we observe the opening of an insulating gap that expands to 14 meV at 2 K. Within the gap, we image the formation of linearly dispersing surface states with effective masses reaching 410 ± 20 m_e (where me is the mass of the electron). Our findings demonstrate the presence of correlation-driven heavy surface states in SmB₆, in agreement with theoretical predictions. Their high effective mass translates to a large density of states near zero energy, which magnifies their susceptibility to the anticipated novel orders and their potentialmore » utility.« less

Authors:

Pirie, Harris  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-5752-5065"

Liu, Yu ^[1]; Soumyanarayanan, Anjan  ^[2];

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• Search DOE PAGES for ORCID "0000-0003-2680-6005"

Chen, Pengcheng ^[1]; He, Yang ^[1]; Yee, M. M. ^[1]; Rosa, P. F. S. ^[3]; Thompson, J. D. ^[3]; Kim, Dae-Jeong ^[4]; Fisk, Z. ^[4]; Wang, Xiangfeng  ^[5];

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• Search DOE PAGES for ORCID "0000-0001-9845-1659"

Paglione, Johnpierre ^[5]; Morr, Dirk K.  ^[6];

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• Search DOE PAGES for ORCID "0000-0003-3692-2835"

Hamidian, M. H.  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-6169-8073"

Hoffman, Jennifer E.  ^[1]

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• Search DOE PAGES for ORCID "0000-0003-2752-5379"

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+ Show Author Affiliations

1. Harvard Univ., Cambridge, MA (United States)
2. Harvard Univ., Cambridge, MA (United States); Ministry of Trade and Industry (Singapore)
3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
4. Univ. of California, Irvine, CA (United States)
5. Univ. of Maryland, College Park, MD (United States)
6. Univ. of Illinois, Chicago, IL (United States)

Publication Date:

Mon Nov 11 00:00:00 EST 2019

Research Org.:

Univ. of Illinois, Chicago, IL (United States); Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); US Air Force Office of Scientific Research (AFOSR); Gordon and Betty Moore Foundation (GBMF); National Science Foundation (NSF)

OSTI Identifier:

1618816

Alternate Identifier(s):

OSTI ID: 1735891

Report Number(s):

LA-UR-18-28712
Journal ID: ISSN 1745-2473; TRN: US2106823

Grant/Contract Number:  

FG02-05ER46225; DMR-1106023; DMR-1410480; FA9550-14-1-0332; GBMF4419; 89233218CNA000001

Resource Type:

Accepted Manuscript

Journal Name:

Nature Physics

Additional Journal Information:

Journal Volume: 16; Journal Issue: 1; Journal ID: ISSN 1745-2473

Publisher:

Nature Publishing Group (NPG)

Country of Publication:

United States

Language:

English

Subject:

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; Material Science