Interplane relaxation and the bilayer coupling in Y$_2$Ba$_4$Cu$_7$O$_{15}$

TL;DR

This paper investigates the interplane relaxation and bilayer coupling in Y$_2$Ba$_4$Cu$_7$O$_{15}$, aiming to understand the spin gap phenomenon in underdoped cuprates through theoretical predictions and proposed experiments.

Contribution

It introduces a method to estimate bilayer coupling strength via interplane relaxation experiments and provides detailed predictions for relaxation rate behavior.

Findings

Predicted size and temperature dependence of interplane relaxation rate.

Suggested interplane relaxation experiment to measure bilayer coupling.

Insights into the spin gap presence in bilayer cuprates.

Abstract

The origin of the spin gap in the underdoped cuprate superconductors is still mysterious. Experimental evidence from neutron scattering and NMR experiments indicates that the spin gap might be present only in the bilayer compounds. A naive calculation for a two plane Heisenberg model locates the order-disorder transition only for very large exchange coupling between the bilayers. We propose a interplane relaxation experiment which might quantitatively estimate the strength of the bilayer coupling. We make detailed predictions for the size and the temperature dependence of the interplane relaxation rate.