Incommensurate Magnetic Fluctuations in YBa2Cu3O6.6

TL;DR

This study uses inelastic neutron scattering to reveal incommensurate low-frequency magnetic fluctuations in YBa2Cu3O6.6 below its critical temperature, showing a shift from antiferromagnetic order and a temperature-dependent susceptibility increase.

Contribution

It provides direct experimental evidence of incommensurate magnetic fluctuations in YBa2Cu3O6.6, advancing understanding of magnetic behavior in high-temperature superconductors.

Findings

Magnetic fluctuations are incommensurate at low temperatures.

Susceptibility increases below Tc at incommensurate positions.

Magnetic fluctuations at commensurate points are suppressed.

Abstract

We use inelastic neutron scattering to demonstrate that at low temperatures, the low frequency magnetic fluctuations in YBa_2Cu_3O_{6.6} ($T_c=62.7$ K) are incommensurate, being found at positions displaced by $\pm\delta$ ($0.057\pm 0.006$ r.l.u.) along the $[\pi,\pi]$ direction from the wave vector $(\pi,\pi)$ associated with the antiferromagnetic order of the parent insulator, YBa_2Cu_3O_{6}. The dynamical susceptibility $\chi''(q,\omega)$ at the incommensurate positions increases on cooling below $T_c$, accompanied by a suppression of magnetic fluctuations at the commensurate points.