Direct observation of multiple spin zeroes in the underdoped high temperature superconductor YBa2Cu3O6+x

TL;DR

This study directly observes multiple spin zeroes in quantum oscillations of underdoped YBa2Cu3O6+x, revealing complex Fermi surface behavior and anisotropic g-factors in high-temperature superconductors.

Contribution

It provides the first direct observation of multiple spin zeroes in this material, indicating multiple Fermi surface components and anisotropic g-factors.

Findings

Multiple spin zeroes observed in quantum oscillations.

Evolution of spin zero positions with magnetic field.

Evidence for multiple Fermi surface components and anisotropic g-factors.

Abstract

We report the direct observation of multiple `spin zeroes' in angle-dependent magnetic quantum oscillations measured up to 85T in YBa2Cu3O6+x, at which the amplitude falls to a deep minimum accompanied by a phase inversion of the measured quantum oscillations, enabling the product of the effective mass and effective g-factor m*g* to be tightly constrained. We find an evolution of the location of the spin zeros with applied magnetic field, and suggest that this effect and the absence of a spin zero at low angles can be produced by more than one Fermi surface component, and an effective g-factor with a subtle anisotropy between in-plane and out-of-plane crystalline directions.