# Groupe de Physique Statistique

## Equipe 106, Institut Jean Lamour

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### Articles dans des revues à comité de lecture

 Quantum phase transition in the spin-anisotropic quantum spherical model Wald S., Henkel M. J. Stat. Mech. (2015) P07006 DOI : 10.1088/1742-5468/2015/07/P07006 ArXiv : arxiv:1503.06713 [PDF] Motivated by an analogy with the spin anisotropies in the quantum XY chain and its reformulation in terms of spin-less Majorana fermions, its bosonic analogue, the spin-anisotropic quantum spherical model, is introduced. The exact solution of the model permits to analyse the influence of the spin-anisotropy on the phase diagram and the universality of the critical behaviour in a new way, since the interactions of the quantum spins and their conjugate momenta create new effects. At zero temperature, a quantum critical line is found, which is in the same universality class as the thermal phase transition in the classical spherical model in $d+1$ dimensions. The location of this quantum critical line shows a re-entrant quantum phase transition for dimensions $1 < d < 2.065$ .