ELECTRON-PARAMAGNETIC-RES OF MN-2+ DOPED SINGLE-CRYSTALS OF NI(NH42) (SO4)2-6H2O AND NISO4-7H2O

X‐band EPR measurements are reported on single crystals of Ni(NH4)2(SO4)2 · 6 H2O and NiSO4n · 7 H2O doped by Mn2+ ions at various temperatures. The absolute sings of the spin Hamiltonia parameters are determined from liquid helium temperature data. A study is made of the variation of linewidths with temperature, as well as with the magnitude of the static magnetic field. The spin Hamiltonian parameters are evaluated rigorously from a simultaneous fitting of the data obtained for several orientations of the static magnetic field, using the method of least‐squares fitting and numerical diagonalization of the spin Hamiltonian matrix appropriate to electronnuclear spin coupled systems. Copyright © 1979 WILEY‐VCH Verlag GmbH & Co. KGaA