Spectroscopy of kondo and spin-flip scattering: High-field tunneling studies of schottky-barrier junctions

E. L. Wolf, D. L. Losee

Research output: Contribution to journalArticle

Abstract

A comprehensive study of the energy, temperature, and magnetic field dependence of the anomalous Kondo and spin-flip conductances G(3)(V) and G(2)(V), in vacuum-cleaved metal-semiconductor tunnel junctions is reported. Localized Anderson magnetic moments are characteristic of Schottky barriers at donor concentrations a few times the Mott critical concentration Nc. These moments, coupled to the conduction electrons in the semiconductor by the s-d exchange interaction -2JS→•σ→, are lightly screened neutral donors at the inner edge of the depletion region. The background conductance in vacuum-cleaved junctions on Si: (1.6×1019 cm-3 donors) agrees satisfactorily with the parabolic barrier model, extended to the thin-barrier limit. A detailed study shows the energy dependence of the zero-bias Kondo scattering peak G(3)(V) to be in good agreement with the third-order perturbation theory of Kondo and Appelbaum. High magnetic field studies confirm that a large negative g shift Δg=2JρF∼-1. 0 and related broadening Γ=π(JρF)2gμBH of the Zeeman transition of the local moment occur via the exchange interaction. The broadening Γ additionally produces, for ΓkBT, a quenching of the Kondo scattering peak from -logT to -log(ΓkB). The directly measured parameters JρF and E0 determine a divergence temperature TK=(E0kB)×exp(1JρF)=(2±1)°K, significantly higher than an upper bound ∼0.5°K, indicated by the observed accurate logT dependence of G(3)(0) to 0.4°K. The discrepancy is removed by assuming simultaneous potential and exchange scattering in a ratio determined via Appelbaum's theory from the observed ratio G(3)G(2). In summary, the tunneling spectra and an extended Kondo-Appelbaum perturbation theory, including the implied g shift, broadening Γ, and an added potential scattering, are in good agreement.

Original languageEnglish (US)
Pages (from-to)3660-3687
Number of pages28
JournalPhysical Review B
Volume2
Issue number9
DOIs
StatePublished - 1970

Fingerprint

Spectroscopy
Scattering
Exchange interactions
scattering
spectroscopy
perturbation theory
Vacuum
Semiconductor materials
Magnetic fields
moments
vacuum
Tunnel junctions
shift
Magnetic moments
magnetic fields
tunnel junctions
conduction electrons
Quenching
divergence
depletion

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Spectroscopy of kondo and spin-flip scattering : High-field tunneling studies of schottky-barrier junctions. / Wolf, E. L.; Losee, D. L.

In: Physical Review B, Vol. 2, No. 9, 1970, p. 3660-3687.

Research output: Contribution to journalArticle

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