Thermodynamics of the frustrated one-dimensional spin-12Heisenberg ferromagnet in a magnetic field

Abstract

We calculate the low-temperature thermodynamic quantities (magnetization, correlation functions, transverse and longitudinal correlation lengths, spin susceptibility, and specific heat) of the frustrated one-dimensional spin-half ${J}_{1}$-${J}_{2}$ Heisenberg ferromagnet, i.e., for ${J}_{2}<0.25|{J}_{1}|$, in an external magnetic field using a second-order Green-function formalism and full diagonalization of finite systems. We determine power-law relations for the field dependence of the position and the height of the maximum of the uniform susceptibility. Considering the specific heat at low magnetic fields, two maxima in its temperature dependence are found.