Magnetic resonance in a cubic Γ 3 (E) doublet system III. Electron spin resonance of Ho 3+ , Gd 3+ , Dy 3+ , Er 3+ and Yb 3+ in Cs 2 NaHoCl 6

Abstract

In Cs 2 NaHoCl 6 the Ho 3+ ion occupies a site of cubic symmetry, and the ground state produced by the crystal field splitting of the 4f 10 , 5 I 8 manifold is a ‘non-magnetic’ Γ 3 doublet. When a field B is applied, the doublet is split by the quadratic Zeeman effect, and transitions between the two levels of the doublet become allowed at a frequency and with an intensity each proportional to B 2. At a frequency of 9.6 GHz the e. s. r. spectrum of the Ho 3+ ion shows a single broad line, with the unusual anisotropic behaviour predicted for a Γ 3 doublet in cubic symmetry (see paper I). No hyperfine splitting is resolved, and the linewidth parameter ∆ v is of order 10 GHz, independent of orientation. The centre of the line occurs at a field consistent with that calculated from n. m. r. measurements (paper II), after a correction is applied for the anomalous line shape. The e. s. r. spectra of Gd 3+ , Dy 3+ , Er 3+ , Yb 3+ , present as impurities, also show cubic symmetry, with spin Hamiltonian parameters close to those observed in analogous compounds such as Cs 2 NaYCl 6 .