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Title: An effect of Sm vacancies on the hybridization gap in topological Kondo insulator candidate SmB 6

Abstract

A necessary element for the predicted topological state in Kondo insulator SmB 6 is the hybridization gap which opens in this compound at low temperatures. Here, in this work, we present a comparative study of the in-gap density of states due to Sm vacancies by Raman scattering spectroscopy and heat capacity for samples where the number of Sm vacancies is equal to or below 1%. We demonstrate that hybridization gap is very sensitive to the presence of Sm vacancies. Lastly, at the amount of vacancies above 1% the gap fills in with impurity states and low temperature heat capacity is enhanced.

Authors:
 [1];  [1];  [1];  [1]; ORCiD logo [2];  [3];  [1]
  1. Johns Hopkins Univ., Baltimore, MD (United States)
  2. Univ. of California, Irvine, CA (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division
OSTI Identifier:
1416316
Report Number(s):
LA-UR-17-30687
Journal ID: ISSN 0921-4526
Grant/Contract Number:
AC52-06NA25396; FG02-08ER46544
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physica. B, Condensed Matter
Additional Journal Information:
Journal Name: Physica. B, Condensed Matter; Journal ID: ISSN 0921-4526
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Topological insulator; Kondo insulator; Hybridization gap; Raman scattering

Citation Formats

Valentine, Michael E., Koohpayeh, Seyed, Phelan, W. Adam, McQueen, Tyrel M., Rosa, Priscila Ferrari Silveira, Fisk, Zachary, and Drichko, Natalia. An effect of Sm vacancies on the hybridization gap in topological Kondo insulator candidate SmB6. United States: N. p., 2017. Web. doi:10.1016/j.physb.2017.10.051.
Valentine, Michael E., Koohpayeh, Seyed, Phelan, W. Adam, McQueen, Tyrel M., Rosa, Priscila Ferrari Silveira, Fisk, Zachary, & Drichko, Natalia. An effect of Sm vacancies on the hybridization gap in topological Kondo insulator candidate SmB6. United States. doi:10.1016/j.physb.2017.10.051.
Valentine, Michael E., Koohpayeh, Seyed, Phelan, W. Adam, McQueen, Tyrel M., Rosa, Priscila Ferrari Silveira, Fisk, Zachary, and Drichko, Natalia. 2017. "An effect of Sm vacancies on the hybridization gap in topological Kondo insulator candidate SmB6". United States. doi:10.1016/j.physb.2017.10.051.
@article{osti_1416316,
title = {An effect of Sm vacancies on the hybridization gap in topological Kondo insulator candidate SmB6},
author = {Valentine, Michael E. and Koohpayeh, Seyed and Phelan, W. Adam and McQueen, Tyrel M. and Rosa, Priscila Ferrari Silveira and Fisk, Zachary and Drichko, Natalia},
abstractNote = {A necessary element for the predicted topological state in Kondo insulator SmB6 is the hybridization gap which opens in this compound at low temperatures. Here, in this work, we present a comparative study of the in-gap density of states due to Sm vacancies by Raman scattering spectroscopy and heat capacity for samples where the number of Sm vacancies is equal to or below 1%. We demonstrate that hybridization gap is very sensitive to the presence of Sm vacancies. Lastly, at the amount of vacancies above 1% the gap fills in with impurity states and low temperature heat capacity is enhanced.},
doi = {10.1016/j.physb.2017.10.051},
journal = {Physica. B, Condensed Matter},
number = ,
volume = ,
place = {United States},
year = 2017,
month =
}

Journal Article:
Free Publicly Available Full Text
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  • There has been considerable interest in exploiting the spin degrees of freedom of electrons for potential information storage and computing technologies. Topological insulators (TIs), a class of quantum materials, have special gapless edge/surface states, where the spin polarization of the Dirac fermions is locked to the momentum direction. This spin–momentum locking property gives rise to very interesting spin-dependent physical phenomena such as the Edelstein and inverse Edelstein effects. However, the spin injection in pure surface states of TI is very challenging because of the coexistence of the highly conducting bulk states. Here, we experimentally demonstrate the spin injection and observemore » the inverse Edelstein effect in the surface states of a topological Kondo insulator, SmB 6. At low temperatures when only surface carriers are present, a clear spin signal is observed. Moreover, the magnetic field angle dependence of the spin signal is consistent with spin–momentum locking property of surface states of SmB6.« less
  • Three-dimensional (3D) topological insulators (TI) are a new state of quantum matter in which surface states reside in the bulk insulating energy bandgap and are protected by time-reversal symmetry. It is possible to create an energy bandgap as a consequence of the interaction between the conduction band and valence band surface states from the opposite surfaces of a TI thin film, and the width of the bandgap can be controlled by the thin film thickness. The formation of an energy bandgap raises the possibility of thin-film TI-based metal-oxide-semiconductor field-effect-transistors (MOSFETs). In this paper, we explore the performance of MOSFETs basedmore » on thin film 3D-TI structures by employing quantum ballistic transport simulations using the effective continuous Hamiltonian with fitting parameters extracted from ab-initio calculations. We demonstrate that thin film transistors based on a 3D-TI structure provide similar electrical characteristics compared to a Si-MOSFET for gate lengths down to 10 nm. Thus, such a device can be a potential candidate to replace Si-based MOSFETs in the sub-10 nm regime.« less
  • Cited by 4
  • We have investigated the low temperature conducting state of two Kondo insulators, SmB 6 and Ce 3Bi 4Pt 3, which have been theoretically predicted to host topological surface states. Through comparison of the speci c heat of as-grown and powdered single crystals of SmB 6, we show that the residual term that is linear in temperature is not dominated by any surface state contribution, but rather is a bulk property. In Ce 3Bi 4Pt 3, we find that the Hall coefficient is independent of sample thickness, which indicates that conduction at low temperatures is dominated by the bulk of themore » sample, and not by a surface state. The low temperature resistivity of Ce 3Bi 4Pt 3 is found to monotonically decrease with low concentrations of disorder introduced through ion-irradiation. This is in contrast to SmB 6, which is again indicative of the contrasting origins of the low temperature conduction. In SmB 6, we also show that the effect of low concentrations of irradiation damage of the surface with Fe + ions is qualitatively consistent with damage with non-magnetic ions.« less
  • Cited by 9