• decoration-iteration transformation;
  • exact results;
  • four-spin interaction;
  • Ising–Heisenberg diamond chain;
  • phase diagram


A symmetric spin-1/2 Ising–Heisenberg diamond chain with the Ising four-spin interaction is exactly solved by means of the generalized decoration-iteration mapping transformation. The ground state, the magnetization process and thermodynamics are particularly examined for the case of antiferromagnetic pair interactions (Ising and isotropic Heisenberg ones). It is shown that an interplay between pair interactions, the four-spin interaction and the external magnetic field gives rise to several quantum ground states with entangled spin states in addition to some semi-classically ordered ones. Besides, the temperature dependence of the magnetic susceptibility multiplied by the temperature is studied and the interesting triple-peak specific heat curve is also detected when considering the zero-field region rather close to the triple point, where three different ground states coexist.