ESR studies of nearest neighbor Cr3+ pairs in MgO

Abstract

Nearest neighbor Cr³⁺ pairs in MgO have been studied by ESR techniques. The spectrum associated with the S=2 spin state was observed. The appropriate spin Hamiltonian for the system is H=βH⋅g⋅S + D_s{S²_z−1/3 S (S+1) }, where the z axis is along 〈110〉. The axially symmetric D tensor was measured to be 0.182±0.009 cm⁻¹, 0.206±0.009 cm⁻¹, and 0.231±0.009 cm⁻¹ for the S=2 spin state. In addition, the temperature dependence of D_s was obtained and was attributed to thermal expansion of the crystal lattice.