Thermodynamic and transport properties of the one-dimensional S = 1/2 antiferromagnet Yb₄As₃

The semimetallic quasi-one-dimensional S = 1/2 antiferromagnet Yb₄As₃ has been studied by performing low-temperature (T) and high magnetic-field (B) measurements of the specific heat, C(T,B), magnetization, M(T,B), AC-susceptibility, χ_AC(T,B), and electrical resistivity, ρ(T,B). At finite transverse magnetic fields, a gap Δ(B) is induced in the low-energy magnetic excitation spectrum. Our C(T,B) measurements reveal a Δ(B)∼B^2/3 dependence for B≤9 T, in accordance with predictions of the quantum sine-Gordon model. At higher fields the Δ(B) curve levels-off gradually. In the isothermal magnetization taken at 0.6 K no saturation occurs up to 60 T. We also present new results on spin-glass behavior below 0.15 K caused by a weak ferromagnetic interchain coupling and disorder. Finally, we concentrate on the electrical transport properties. Shubnikov-de Haas oscillations, arising from a low-density system of mobile As-4p holes, are recorded in magnetic fields up to 60 T. We estimate the effective mass and the mean-free path of these carriers and discuss spin-splitting effects.