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Title: Impurity bands in Kondo insulators

Abstract

Kondo insulators like Ce{sub 3}Bi{sub 4}Pt{sub 3} and CeNiSn are compounds with small-band-gap semiconductor properties. Nonmagnetic impurities, so-called Kondo holes, break the translational invariance and hence the coherence of the ground state. Isolated impurities give rise to a bound state in the gap, which pins the Fermi level and has magnetic properties (Curie susceptibility and Schottky anomaly in the specific heat). A finite concentration of Kondo holes gives rise to an impurity band inside the gap of the {ital f}-electron density of states, whose height and width are proportional to {radical}{ital c} for small concentrations. The specific heat is proportional to {ital T} at very low temperatures and the susceptibility is Pauli-like at low {ital T}. The correlations within the {ital f} band are introduced via a self-energy, evaluated to second-order perturbation in {ital U}. We use the (1/{ital d})-expansion method of Schweitzer and Czycholl to leading order in which the {bold k} integrations are properly carried out, but the {bold k} dependence of the self-energy is neglected. The main effect of {ital U} is to narrow the gap, as well as the impurity band.

Authors:
 [1]
  1. Department of Physics and Center for Materials Research and Technology, Florida State University, Tallahassee, Florida 32306 (United States)
Publication Date:
OSTI Identifier:
5071913
DOE Contract Number:  
FG05-91ER45443
Resource Type:
Journal Article
Journal Name:
Physical Review, B: Condensed Matter; (United States)
Additional Journal Information:
Journal Volume: 46:2; Journal ID: ISSN 0163-1829
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; KONDO EFFECT; TEMPERATURE EFFECTS; BISMUTH COMPOUNDS; BOUND STATE; CERIUM COMPOUNDS; ENERGY GAP; MAGNETIC SUSCEPTIBILITY; PERTURBATION THEORY; PLATINUM COMPOUNDS; SPECIFIC HEAT; MAGNETIC PROPERTIES; PHYSICAL PROPERTIES; RARE EARTH COMPOUNDS; THERMODYNAMIC PROPERTIES; TRANSITION ELEMENT COMPOUNDS; 360104* - Metals & Alloys- Physical Properties

Citation Formats

Schlottmann, P. Impurity bands in Kondo insulators. United States: N. p., 1992. Web. doi:10.1103/PhysRevB.46.998.
Schlottmann, P. Impurity bands in Kondo insulators. United States. https://doi.org/10.1103/PhysRevB.46.998
Schlottmann, P. Wed . "Impurity bands in Kondo insulators". United States. https://doi.org/10.1103/PhysRevB.46.998.
@article{osti_5071913,
title = {Impurity bands in Kondo insulators},
author = {Schlottmann, P},
abstractNote = {Kondo insulators like Ce{sub 3}Bi{sub 4}Pt{sub 3} and CeNiSn are compounds with small-band-gap semiconductor properties. Nonmagnetic impurities, so-called Kondo holes, break the translational invariance and hence the coherence of the ground state. Isolated impurities give rise to a bound state in the gap, which pins the Fermi level and has magnetic properties (Curie susceptibility and Schottky anomaly in the specific heat). A finite concentration of Kondo holes gives rise to an impurity band inside the gap of the {ital f}-electron density of states, whose height and width are proportional to {radical}{ital c} for small concentrations. The specific heat is proportional to {ital T} at very low temperatures and the susceptibility is Pauli-like at low {ital T}. The correlations within the {ital f} band are introduced via a self-energy, evaluated to second-order perturbation in {ital U}. We use the (1/{ital d})-expansion method of Schweitzer and Czycholl to leading order in which the {bold k} integrations are properly carried out, but the {bold k} dependence of the self-energy is neglected. The main effect of {ital U} is to narrow the gap, as well as the impurity band.},
doi = {10.1103/PhysRevB.46.998},
url = {https://www.osti.gov/biblio/5071913}, journal = {Physical Review, B: Condensed Matter; (United States)},
issn = {0163-1829},
number = ,
volume = 46:2,
place = {United States},
year = {1992},
month = {7}
}