Magnetic-field-induced spin excitations and renormalized spin gap of the underdoped superconductor La$_{1.895}$Sr$_{0.105}$CuO$_{4}$

TL;DR

This study uses neutron scattering to explore how magnetic fields influence spin excitations and the spin gap in underdoped LSCO, revealing a field-induced enhancement and a strongly renormalized spin gap.

Contribution

It demonstrates the magnetic field's effect on spin excitations and the renormalization of the spin gap in underdoped LSCO, providing new insights into its magnetic properties.

Findings

Field enhances spectral weight at finite energies

Spin gap is strongly downward renormalized by magnetic field

Anomaly in low-energy peak shifts with magnetic field

Abstract

High-resolution neutron inelastic scattering experiments in applied magnetic fields have been performed on La$_{1.895}$Sr$_{0.105}$CuO$_{4}$ (LSCO). In zero field, the temperature dependence of the low-energy peak intensity at the incommensurate momentum-transfer $\mathbf{Q}^{\ }_{\mathrm{IC}}=(0.5,0.5\pm\delta,0),(0.5\pm\delta,0.5,0)$ exhibits an anomaly at the superconducting $T^{\}_{c}$ which broadens and shifts to lower temperature upon the application of a magnetic field along the c-axis. A field-induced enhancement of the spectral weight is observed, but only at finite energy transfers and in an intermediate temperature range. These observations establish the opening of a strongly downward renormalized spin gap in the underdoped regime of LSCO. This behavior contrasts with the observed doping dependence of most electronic energy features.