Properties of spin-1/2 antiferromagnetic Heisenberg chain with dimerization and exchange anisotropy

Using Jordan-Wigner transformation and Abelian bosonization approach, gener alized sine-Gordon (SG) equation can be derived from the spin-1/2 antiferro magnetic, Heisenberg chain (AFHC) with dimerization and exchange anisotropy . Applying the scalar field quantum mechanical approach to the SG equation and approximating cosine term at finite temperature, we can obtain the exci tation spectrum of boson quasi-particle. We studied the effects of the dime rization and the exchange anisotropy on the formation of the energy gap at zero and nonzero temperature, respectively. We also studied the thermodynam ic properties of the spin-1/2 AFHC and found the behavior of the energy gap and specific heat are analogous to those of the BCS superconducting state. (C) 2001 Published by Elsevier Science B.V.