Field induced quantum phase transition in the anisotropic spin ladder

We have studied the quantum phase transition between antiferromagnetic and spin liquid phases for field induced quasi-one dimensional spin ladder model Hamiltonian. Using bond operator formalism, the original spin Hamiltonian is mapped to bosonic one. Green's function approach has been implemented to get the low energy spectrum and the corresponding structure factor. The critical field (Bc) for a fixed coupling exchange between two rungs is found based on the Bose–Einstein condensation of quasi-particles (triplons) which takes place when the spin excitation spectrum vanishes at the antiferromagnetic wave vector. We have investigated the effect of both intersite (δδ) and local (ΔΔ) anisotropy on the critical field, critical coupling exchange and transverse static structure factor of the field induced quasi-one dimensional antiferromagnetic anisotropic spin ladder model at zero temperature. We have also studied the divergent behavior of static spin structure factor when magnetic field approaches the critical point.

► The calculation of quantum critical field of spin ladder Hamiltonian by Green's function approach.
► The study of behavior of energy gap of spin excitation spectrum versus field and anisotropies.
► The investigation of behavior of transverse structure factor in terms of magnetic field.