Hyperfine Interactions for Cu Nuclei in (C2H5NH3)2CuCl4

Abstract

From the angular dependence of the Cu 63 NMR frequency in the magnetically ordered state of (C 2 H 5 NH 3 ) 2 CuCl 4 , the parameters in the Cu 63 nuclear spin Hamiltonian are determined as follows; H x =-28.5 kOe, H y =-27.7 kOe, H z =-189.6 kOe, ν Q =6.00 MHz and η=-0.1. From these values, the Fermi contact, dipolar and orbital fields are separately estimated as H F =-114 kOe, H d =+24.4 kOe, H l // =-8.9 kOe and H l ⊥ =-6.3 kOe. The disagreement of the dipolar and orbital fields with the theoretical estimations is found and is interpreted as mainly due to the reduction of 3d spin caused by the electron transfer from the Cl - ions. On the contrary, it is shown that the Fermi contact field is hardly affected by the ligand ions.