3D-xy critical properties of YBa2Cu4O8 and magnetic field induced 3D to 1D crossover

TL;DR

This study investigates the critical behavior of YBa2Cu4O8 under magnetic fields, revealing a 3D-xy critical regime and a magnetic field induced crossover to 1D behavior, challenging mean-field phase transition predictions.

Contribution

It provides experimental evidence for a magnetic field induced 3D to 1D crossover and analyzes the critical phenomena using scaling forms in YBa2Cu4O8.

Findings

Confirmation of 3D-xy critical behavior in YBa2Cu4O8

Observation of a magnetic field induced 3D to 1D crossover

No continuous phase transition along H_c2 lines as mean-field theory predicts

Abstract

We present reversible magnetization data of a YBa2Cu4O8 single crystal and analyze the evidence for 3D-xy critical behavior and a magnetic field induced 3D to 1D crossover. Remarkable consistency with these phenomena is observed in agreement with a magnetic field induced finite size effect, whereupon the correlation length transverse to the applied magnetic field cannot grow beyond the limiting magnetic length scale L_H. By applying the appropriate scaling form we obtain the zero-field critical temperature, the 3D to 1D crossover, the vortex melting line and the universal ratios of the related scaling variables. Accordingly there is no continuous phase transition in the (H,T)-plane along the H_c2-lines as predicted by the mean-field treatment.