The temperature dependence of the hyperfine interaction of the transition metal osmium in a gadolinium host matrix

Abstract

Integral perturbed angular correlations of the 931-155keVγγ-cascade of¹⁸⁸Os in Gd have been measured. With this technique the combined magnetic and electric hyperfine interaction of the 155 keV level of¹⁸⁸Os as an impurity in a Gd host has been studied as a function of temperature. The result for the electric field gradient of Os in Gd at 300 K is:

$$\left| {V_{zz} \left( {Os:\underline {Gd} } \right)} \right| = \left( {12.8_{ - 1.9}^{ + 3.1} } \right) \cdot 10^{17} {V \mathord{\left/ {\vphantom {V {cm^2 }}} \right. \kern-\nulldelimiterspace} {cm^2 }}.$$

For the magnetic hyperfine field at 4.2 K the value

$$H_{hf} \left( {Os:\underline {Gd} } \right) = - 134\left( {26} \right)kG$$

was obtained.

Sign and magnitude of the magnetic hyperfine field suggest the existence of a localized moment of about −0.4 µ _B at the site of Os in Gd.

With increasing temperature the magnetic hyperfine field decreases much stronger than the magnetization of the host. Possible explanations for this anomalous temperature dependence are discussed.