Magnetization, Nernst effect and vorticity in the cuprates

TL;DR

This paper investigates the pseudogap phase in cuprates, revealing vortex-like excitations above Tc, and provides insights into the phase transition, high-field behavior, and vortex states in underdoped samples.

Contribution

It introduces evidence for vortex excitations above Tc and estimates the depairing field, advancing understanding of the cuprate phase diagram and transition mechanisms.

Findings

Existence of vortex-like excitations above Tc

Large depairing field Hc2 estimated to be 40-100 T

Observation of vortex liquid in underdoped LSCO at T→0

Abstract

Nernst and magnetization experiments reveal the existence of a large region of the cuprate phase diagram above the $T_c$ curve in which vorticity and weak diamagnetism exist without phase coherence. We discuss the implication that the transition at $T_c$ is caused by the loss of long-range phase coherence caused by spontaneous vortex creation. Below $T_c$, these measurements provide an estimate of the depairing field $H_{c2}$ which is found to be very large (40-100 T depending on doping). We discuss the high-field Nernst and magnetization results, binding energy, and the phase diagram of hole-doped cuprates. Some new magnetization results on the vortex liquid in very underdoped LSCO in the limit $T\to 0$ are reported as well.