Magnon and Soliton Excitations in the Carrier-Poor, One-Dimensional S=1/2 Antiferromagnet Yb_{4}As_{3}

• Authors: F. Steglich , M. Köppen , P. Gegenwart , T. Cichorek , B. Wand , M. Lang , P. Thalmeier , B. Schmidt , H. Aoki , A. Ochiai
• Languages of publication: EN

Abstracts

EN

The semimetallic quasi-one-dimensional S=1/2 Heisenberg antiferromagnet Yb_{4}As_{3} was studied by low-temperature measurements of the specific heat C(T,B), thermal expansion α(T,B), and thermal conductivity ĸ(T,B). At finite magnetic fields (B≤12 T) we observed the following distinct anomalies: (1) the magnon contribution to C(T,0), γ T, with large coefficient γ ≈ 200 mJ/(K^{2}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 ĸ(T,B= const)/ĸ(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 E_{S} ~ B^{ν}, 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.

Keywords

EN

75.30.Mb; 65.50.+m; 65.70.+y

Discipline

• 75.30.Mb: Valence fluctuation, Kondo lattice, and heavy-fermion phenomena(see also 71.27.+a Strongly correlated electron systems, heavy fermions; for heavy-fermion superconductors, see 74.70.Tx)

• Publisher: Institute of Physics, Polish Academy of Sciences
• Journal: Acta Physica Polonica A
• Year: 2000
• Volume: 97
• Issue: 1
• Pages: 91-100

Dates

published

2000-01

Contributors

author

F. Steglich

• Max-Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany

author

M. Köppen

• Max-Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany

author

P. Gegenwart

• Max-Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany

author

T. Cichorek

• Max-Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany

author

B. Wand

• Max-Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany

author

M. Lang

• Max-Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany

author

P. Thalmeier

• Max-Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany

author

B. Schmidt

• Max-Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany

author

H. Aoki

• Department of Material Science and Technology, Niigata 950-21, Japan

author

A. Ochiai

• Department of Material Science and Technology, Niigata 950-21, Japan

Identifiers

DOI

10.12693/APhysPolA.97.91