High energy spin excitations in YBa_2 Cu_3 O_{6.5}

TL;DR

This study uses inelastic neutron scattering to comprehensively analyze the spin excitations in underdoped YBa_2Cu_3O_{6.5}, revealing energy- and temperature-dependent behaviors of different symmetry modes.

Contribution

It provides the first detailed measurement of the dynamical spin susceptibility across a wide energy and temperature range in underdoped YBa_2Cu_3O_{6.5}.

Findings

Detection of two symmetry modes with distinct temperature dependences.

Observation of dispersive high-energy spin excitations.

Quantitative characterization of spin susceptibility over broad conditions.

Abstract

Inelastic neutron scattering has been used to obtain a comprehensive description of the absolute dynamical spin susceptibility $\chi'' (q,\omega)$ of the underdoped superconducting cuprate YBa_2 Cu_3 O_{6.5} ($T_c = 52 K$) over a wide range of energies and temperatures ($2 meV \leq \hbar \omega \leq 120 meV$ and $5K \leq T \leq 200K$). Spin excitations of two different symmetries (even and odd under exchange of two adjacent CuO_2 layers) are observed which, surprisingly, are characterized by different temperature dependences. The excitations show dispersive behavior at high energies.