Magnetic Field Induced Phase Transitions in YBa2Cu4O8

TL;DR

This paper analyzes resistivity measurements in YBa2Cu4O8 under magnetic fields, revealing phase transitions including superconductor-normal and normal-insulator transitions, and identifies a multicritical point with coexisting phases.

Contribution

It applies scaling theory to interpret resistivity data, identifying critical points and phase coexistence in YBa2Cu4O8 under magnetic fields.

Findings

Superconductor to normal transition identified for both field orientations.

Normal to insulator transition occurs at a critical field H_c||a.

A multicritical point with coexisting phases is found.

Abstract

The $c$-axis resistivity measurements in YBa_2Cu_4O_8 from Hussey et al. for magnetic field orientations along the c-axis as well as within the ab-plane are analyzed and interpreted using the scaling theory for static and dynamic classical critical phenomena. We identify a superconductor to normal conductor transition for both field orientations as well as a normal conductor to insulator transition at a critical field H_c||a with dynamical critical exponent z=1, leading to a multicritical point where superconducting, normal conducting and insulating phases coexist.