Magnon and soliton excitations in the carrier-poor, one-dimensional S = 1/2 antiferromagnet Yb4As3

F. Steglich, M. Köppen, P. Gegenwart, T. Cichorek, B. Wand, M. Lang, P. Thalmeier, B. Schmidt, H. Aoki, A. Ochiai

Research output: Contribution to journalConference article

6 Citations (Scopus)

Abstract

The semimetallic quasi-one-dimensional S = 1/2 Heisenberg antiferromagnet Yb4As3 was studied by low-temperature measurements of the specific heat C(T, B), thermal expansion α(T, B), and thermal conductivity κ(T, B). At finite magnetic fields (B ≤ 12 T) we observed the following distinct anomalies: (1) the magnon contribution to C(T, 0), γT, with large coefficient γ ≈ 200 mJ/(K2 mol), becomes strongly reduced with field, and (2) a broad hump in C(T, B = const) is induced at slightly higher temperatures. (3) The latter corresponds to a pronounced peak in α(T, B = const) as well as (4) to a broad minimum in κ(T, B = const)/κ(T, 0). These anomalies are well described by the classical sine-Gordon solution of a one-dimensional Heisenberg antiferromagnet with a weak easy-plane anisotropy. However, the soliton-rest energy deduced from the experimental results depends on the magnetic field like Es ∼ Bν, with an exponent ν ≈ 0.66, while the classical sine-Gordon model requires ν = 1. Thus, our results suggest an alternative description of soliton excitations in an antiferromagnetic S = 1/2 Heisenberg chain in terms of the quantum sine-Gordon model, for which an exponent ν = 2/3 is appropriate.

Original languageEnglish
Pages (from-to)91-100
Number of pages10
JournalActa Physica Polonica A
Volume97
Issue number1
DOIs
Publication statusPublished - 2000 Jan
EventThe European Conference: Physics of Magnetism '99 - Poznan, Poland
Duration: 1999 Jun 211999 Jun 25

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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