Effects of doping in Kondo insulators (invited)

Journal Article · Sun May 15 04:00:00 EDT 1994 · Journal of Applied Physics; (United States)

DOI:https://doi.org/10.1063/1.356720· OSTI ID:7206593

Schlottmann, P ^[1]

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1. Department of Physics, Florida State University, Tallahassee, Florida 32306 (United States)

Kondo insulators like Ce[sub 3]Bi[sub 4]Pt[sub 3] and CeNiSn are compounds with small-gap semiconductor properties. Nonmagnetic impurities, so-called Kondo holes, break the translational invariance and hence the coherence of the ground state. Impurity states can be introduced by (i) substituting the rare earth (actinide) ion or (ii) by replacing (or adding, removing) one of the ligand atoms. Isolated impurities usually give rise to bound states in the gap. Depending on the nature of the impurity (charge neutral or a dopand) the Fermi level is pinned by the impurity level or lies in the gap. In the former case the Kondo hole has magnetic properties (Curie susceptibility and Schottky anomaly in the specific heat), while in the latter situation the properties are nonmagnetic. For a finite concentration of Kondo holes the situations (i) and (ii) are qualitatively different. In (i) it gives rise to an impurity band inside the gap of the semiconductor. The height and width of the impurity band in the [ital f]-electron density of states are proportional to [ital c][sup 1/2] for small concentrations. If the impurities are charge neutral the Fermi level lies in the impurity band giving rise to a specific heat proportional to [ital T] and a Pauli-like susceptibility. If the impurities dope the bands the properties remain semiconducting with a strongly reduced gap. For ligand impurities [case (ii)] tails of impurity states develop close to the gap edges, suppressing in this way the gap. The system remains a semiconductor if the impurities are charge neutral, but [ital C][proportional to][ital T] and [chi] is finite if they are dopands.

• DOE Contract Number: FG05-91ER45443
• OSTI ID: 7206593
• Journal Information: Journal of Applied Physics; (United States), Journal Name: Journal of Applied Physics; (United States) Vol. 75:10; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104 -- Metals & Alloys-- Physical Properties
665400* -- Quantum Physics Aspects of Condensed Matter-- (1992-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALLOYS
BISMUTH COMPOUNDS
CERIUM COMPOUNDS
ELECTRONIC STRUCTURE
IMPURITIES
INTERMETALLIC COMPOUNDS
KONDO EFFECT
MAGNETIC PROPERTIES
MAGNETIC SUSCEPTIBILITY
NICKEL COMPOUNDS
PHYSICAL PROPERTIES
PLATINUM COMPOUNDS
RARE EARTH COMPOUNDS
SPECIFIC HEAT
THERMODYNAMIC PROPERTIES
TIN COMPOUNDS
TRANSITION ELEMENT COMPOUNDS