Specific heat of spin-one-half frustrated Heisenberg ladder

Gang Su ^a,∗ , Huaizhong Xing ^{b ,} Jianbo Wang ^c , Fashen Li ^c

a Department of Physics, Graduate School, Chinese Academy of Sciences, P.O. Box 3908, Beijing 100039, China b Shanghai Institute of Technological Physics, Chinese Academy of Sciences, Shanghai, China c Department of Physics, Lanzhou University, Lanzhou 730000, China Received 7 February 2001; accepted 19 March 2001 Communicated by V.M. Agranovich

Abstract The specific heat of S = 1/2 frustrated Heisenberg antiferromagnetic spin ladder is investigated by means of a modified spinwave theory. It is found that at low temperatures the specific heat shows a round peak, and decays exponentially below the peak temperature. The maximum of the specific heat decreases with increasing the rung-couplings, while it increases with increasing the diagonal couplings. The peak temperature moves to lower temperatures when the rung-coupling is increased, while it shifts to higher temperatures when the diagonal coupling is increased. Our observation is expected to be confirmed experimentally.  2001 Elsevier Science B.V. All rights reserved.

PACS: 75.10.-b; 75.10.Jm; 75.30.Kz