Magnetic Resonance of ZnCr2Se4 with Screw Spin Structure

Abstract

Magnetic resonance of a ZnCr 2 Se 4 single crystal with screw spin structure was observed in the frequency range of 38∼83 GHz at above 4.2 K , mainly at 5.5 K . Frequency and angular dependences of the resonance field were successfully explained by a theory of first order perturbation due to uniaxial anisotropy. Data of the resonance, together with the results of static magnetization measurements, give two isotropic molecular field constants in k space: E (0)- E ( k 0 )=2.15 and E (0)- E (2 k 0 )=-0.01 (mole) and three anisotropy constants: K (0)=0.01 5 , K ( k 0 )=0.10 and K (2 k 0 )=-0.06 (mole). It is demonstrated conclusively that superexchange interaction through more than two Se ions is important in this substance.