Single crystal EPR studies of Cu(II) doped in cadmium sodium sulphate hexahydrate: a case of low hyperfine coupling constant

Single crystal electron paramagnetic resonance studies of Cu(II) doped cadmium sodium sulphate hexahydrate are carried out at room temperature. Angular variation of copper hyperfine lines in the three orthogonal axes shows the presence of a single site in a substitutional position. The spin Hamiltonian parameters calculated from the spectra are: g11=2.070; g22=2.191; g33=2.366; A11=5.96 mT; A22=1.65 mT and A33=8.62 mT. The low value of A33 has been explained by considering considerable admixture of dx2−y2 ground state with dz2 excited state. The admixture coefficients of ground state wave function are: a=0.281; b=0.957; c=0.057; d=0.032; e=−0.032, where a and b correspond to admixture coefficients for dz2 and dx2−y2 respectively. EPR powder spectrum at room temperature and 77 K gives identical spin Hamiltonian parameters, which matched fairly well with the single crystal data. Parameters κ=0.2018; P=142.62×10−4; α2=0.7149; α=0.8455 and α′=0.5982 have also been calculated.