Low-temperature specific heat of a random Heisenberg chain in the large-Slimit

Results are presented for the low-temperature specific heat of a disordered Heisenberg chain with random $\pm J$ interactions in the large-spin limit. The specific heat varies at $T^{2/3}$ with a coefficient that depends on the relative fractions of positive and negative bonds. The coefficient is calculated exactly for the equal-probability distribution. There is also a brief analysis of the destabilizing effects of an applied magnetic field.