We report low-temperature measurements of the specific heat, thermal expansion, and thermal conductivity on the quasi-one-dimensional, effective s = 1/2 Heisenberg antiferromagnet Yb4As3. Distinct field-induced anomalies were found in the above quantities which are well described by the classical sine-Gordon soliton solution for an easy-plane Heisenberg antiferromagnet. Our findings strongly suggest that Yb4As3 represents the first example of an antiferromagnetic S = 1/2 spin-chain system where this type of nonlinear excitation could be identified.
ASJC Scopus subject areas
- Physics and Astronomy(all)