Quantum degradation of the second order phase transition

TL;DR

This study investigates how quantum effects influence the second order phase transition in EuTe, revealing a quantum critical point and the suppression of fluctuations at low temperatures through experimental measurements and theoretical analysis.

Contribution

It provides experimental evidence and theoretical interpretation of quantum degradation of second order phase transitions in EuTe, highlighting the role of effective dimensionality.

Findings

Neel temperature decreases with magnetic field and approaches zero at 76 kOe.

Lambda-type anomalies evolve into simple jumps at high fields and low temperatures.

Data support the quantum concept of increased effective dimensionality suppressing fluctuations.

Abstract

The specific heat, magnetization and thermal expansion of single crystals of antiferromagnetic insulator EuTe, measured at temperatures down to 2 K and in magnetic fields up to 90 kOe, demonstrate non trivial properties. The Neel temperature, being 9.8 K at H=0, decreases with magnetic field and tends to zero at 76 kOe, therefore forming a quantum critical point. The heat capacity and thermal expansion coefficient reveal lambda-type anomalies at the second order magnetic phase transition at low magnetic fields, evolving to simple jumps at high magnetic fields and low temperatures, well described in a fluctuation free mean-field theory. The experimental data and the corresponding analysis favor the quantum concept of effective increasing space dimensionality at low temperatures that suppresses a fluctuation divergence at a second order phase transition.