Thermal conductivity of the one-dimensional S=1/2 antiferromagnet Yb4(As1−P )3 (x=0 and 0.3)

Abstract The thermal conductivity κ of Yb 4 (As 1− x P x ) 3 ( x =0 and 0.3) was measured in the temperature range between 0.1 and 7 K in applied magnetic fields up to 8 T. The fact that κ ( T ) follows, between 0.4 and 3 K, the relation aT + bT 2 confirms our earlier interpretation of the dominating role of magnons both as heat carriers and as scatterers for the phonons. Above 1 K, κ decreases with increasing magnetic field, the opening of a gap in the magnon-excitation spectrum being a possible explanation of this behavior.