Nuclear spin-lattice relaxation studies of Cu$_{2}$O

TL;DR

This study measures the nuclear spin-lattice relaxation rates of copper isotopes in Cu$_2$O across a range of temperatures, revealing distinct temperature dependencies for magnetic and quadrupole relaxation mechanisms.

Contribution

It provides detailed isotopic relaxation rate measurements and estimates the separate contributions of magnetic and quadrupole relaxation processes in Cu$_2$O.

Findings

Quadrupole relaxation rate varies as T^{2.1}

Magnetic relaxation rate varies as T^{1.6} or exponentially with temperature

Discussion of non-degenerate Fermi gas as a relaxation candidate

Abstract

We report the $^{63}$Cu and $^{65}$Cu nuclear spin-lattice relaxation rate measurements of cuprous oxide Cu$_2$O in a zero field Cu nuclear quadrupole resonance at $T$ = 77$-$325 K. From the detailed isotopic measurements of the relaxation rates, we successfully estimated a finite magnetic relaxation rate $^{63}W_M$ and a predominant nuclear quadrupole relaxation rate $^{63}W_Q$. $^{63}W_Q$ changed as $T^{2.1}$, while $^{63}W_M$ changed as $T^{1.6}$ or $T^{\beta}\mathrm{exp}(-\it\Delta/T)$ with $\beta$ = 0.6(3) and $\it\Delta$ = 190(62) K. The nuclear spin scattering process due to a non-degenerate Fermi gas was discussed as a possible candidate of the magnetic relaxation.