Journal of Physics Condensed Matter
The low-temperature specific heat anomaly of the SU(2) invariant 1D Heisenberg antiferromagnet of spin S in a small magnetic field
Kong-Ju-Bock Lee
Abstract
It is expected that the specific heat of the SU(2)-invariant 1D Heisenberg antiferromagnet of spin S is linear to the temperature at low T with the linear coefficient gamma s being a function of field H. The author's main result is that lim H to O gamma s = 1 / 3 (1+ square root S Gamma (S)(e/S) s / pi ) not= lim T to O lim H to O gamma s =2S/(1+S). This extends the previous result for S= 1 / 2 to other spin values. The author also provides an approximate interpolation formula between these two limits as a function of H/T for very small H and T.