Study of Dilute CuEr Alloys by the EPR Method

Abstract

The spectrum of the electron paramagnetic resonance of the Er³⁺ ion in the matrix of metallic copper has been studied at 9.8 GHz in the temperature range from 1.7 to 4.2 K. The spectrum corresponds to the crystal field of cubic symmetry at g = 6.805 ± 0.01; this value agrees with the expected value for the doublet Γ₇. The residual width of the EPR line (T = 0 K) for the even isotopes of erbium was only 4.5 Oe. The temperature and concentration changes in the width of the line indicate the existence of an RKKY interaction between erbium ions. The hyperfine structure (HFS) of the EPR line for the ¹⁶⁷Er isotope has been identified. The positions of separate HFS lines are described with an accuracy of 1.5 Oe by a constant A = 74.25 ± 0.1 Oe. The increase in the accuracy of the determination of the hyperfine splitting of lines of the Er³⁺ ions made it possible to reveal a weak exchange narrowing of the HFS upon an increase of the erbium concentration in these alloys.