Hyperfine interaction in cobalt by high-resolution neutron spectroscopy

TL;DR

This study uses high-resolution neutron spectroscopy to analyze the hyperfine interaction in cobalt, revealing details about its ferromagnetic phase transition, critical behavior, and Curie temperature.

Contribution

It provides precise measurements of the hyperfine splitting and critical exponent in cobalt, improving understanding of its magnetic phase transition.

Findings

Critical exponent β = 0.350 ± 0.002

Curie temperature T_C = 1400 K

Better agreement with 3D Heisenberg model predictions

Abstract

We have investigated the ferromagnetic phase transition of elemental Co by high-resolution neutron backscattering spectroscopy. We monitored the splitting of the nuclear levels by the hyperfine field at the Co nucleus. The energy of this hyperfine splitting is identified as the order parameter of the ferromagnetic phase transition. By measuring the temperature dependence of the energy we determined the critical exponent $\beta = 0.350 \pm 0.002$ and the ferromagnetic Curie temperature of $T_{\text{C}} = 1400$~K. The present result of the critical exponent agrees better with the predicted value (0.367) of the 3-dimensional Heisenberg model than that determined previously by NMR.