Evolution of superconducting correlations within magnetic-field-decoupled CuO(2) layers of La(1.905)Ba(0.095)CuO(4)

TL;DR

This study investigates how superconducting correlations evolve within CuO(2) layers of La(1.905)Ba(0.095)CuO(4) under high magnetic fields, revealing in-plane superconductivity persists despite decoupling of layers and challenging traditional critical field definitions.

Contribution

It demonstrates that superconducting correlations within CuO(2) planes are robust against magnetic fields that decouple the layers, highlighting complex in-plane superconductivity behavior in underdoped cuprates.

Findings

Superconducting correlations within CuO(2) layers remain intact despite interlayer decoupling.

Large amplitude, phase-disordered superconductivity appears within planes around 30 K.

In-plane resistivity drops suggest a superconducting state without interlayer phase coherence.

Abstract

We explore the evolution of superconductivity in La(2-x)Ba(x)CuO(4) with x=0.095 in magnetic fields of up to 35 T applied perpendicular to the CuO(2) planes. Previous work on this material has shown that perpendicular fields enhance both charge and spin stripe order within the planes. We present measurements of the resistivity parallel and perpendicular to the planes, as well as the Hall effect. Measurements of magnetic susceptibility for fields of up to 15 T applied both parallel and perpendicular to the planes provide complementary measures of the superconductivity. We show that fields sufficient to destroy pair tunneling between the planes do not disrupt the superconducting correlations within the planes. In fact, we observe an onset of large amplitude but phase disordered superconductivity within the planes at approximately 30 K that is remarkably insensitive to field. With further cooling, we observe a phase-transition-like drop in the in-plane resistivity to an apparent state of superconductivity, despite the lack of phase coherence between the layers. These observations raise interesting questions concerning the identification of the upper critical field, where pairing is destroyed, in underdoped cuprates.