High-temperature Expansion for Frustrated Magnets: Application to the J1-J2 Model on the BCC Lattice

Abstract

We present the high-temperature expansion up to 11th order for the specific heat C and the uniform susceptibility χ0 and up to 9th order for the structure factor SQ of the frustrated spin-half J1-J2 Heisenberg model on the BCC lattice. We consider ferromagnetic as well as antiferromagnetic nearest-neighbor exchange J1 and frustrating antiferromagnetic next-nearest- neighbor exchange J2. We discuss the influence of frustration on the temperature dependence of these quantities. Furthermore, we use the HTE series to determine the critical temperature Tc as a function of the frustration parameter J2.