Eur. Phys. J. B (2013) 86: 340
https://doi.org/10.1140/epjb/e2013-40407-6

Regular Article

Magnetic-field-induced quantum criticality in a spin-S planar ferromagnet with single-ion anisotropy

¹ Dipartimento di Fisica “E.R. Caianiello”, Università di Salerno, 84084 Fisciano ( Salerno), Italy
² CNISM, Unità di Salerno, 84084 Fisciano ( Salerno), Italy
³ Dipartimento di Fisica, Università di Napoli Federico II, 80125 Napoli, Italy

^a e-mail: mtm@physics.unisa.it

Received: 16 April 2013
Received in final form: 6 June 2013
Published online: 1 August 2013

Abstract

The effects of single-ion anisotropy on quantum criticality in a d-dimensional spin-S planar ferromagnet is explored by means of the two-time Green’s function method. We work at the Tyablikov decoupling level for exchange interactions and the Anderson-Callen decoupling level for single-ion anisotropy. In our analysis a longitudinal external magnetic field is used as the non-thermal control parameter and the phase diagram and the quantum critical properties are established for suitable values of the single-ion anisotropy parameter D. We find that the single-ion anisotropy has sensible effects on the structure of the phase diagram close to the quantum critical point. However, for values of the uniaxial crystal-field parameter below a positive threshold, the conventional magnetic-field-induced quantum critical scenario remains unchanged.