Quantum fluctuation induced ordered phase in the Blume-Capel model

TL;DR

This paper demonstrates that quantum fluctuations can induce an ordered phase in the Blume-Capel model, contrary to typical cases where they destroy order, and identifies a phase transition between quantum paramagnetic and diamagnetic phases.

Contribution

It reveals a novel quantum fluctuation-induced ordered phase in the Blume-Capel model, supported by mean field and quantum Monte Carlo analyses.

Findings

Quantum fluctuation induces an ordered phase in the model.

A phase transition exists between quantum paramagnetic and diamagnetic phases.

Mean field and quantum Monte Carlo methods confirm the results.

Abstract

We consider the Blume-Capel model with the quantum tunneling between the excited states. We find a magnetically ordered phase transition induced by quantum fluctuation in a model. The model has no phase transition in the corresponding classical case. Usually, quantum fluctuation breaks ordered phase as in the case of the transverse field Ising model. However, in present case, an ordered phase is induced by quantum fluctuation. Moreover, we find a phase transition between a quantum paramagnetic phase and a classical diamagnetic phase at zero temperature. We study the properties of the phase transition by using a mean field approximation (MFA), and then, by a quantum Monte Carlo method to confirm the result of the MFA.