Crystal Field Theory of Magnetic Behaviour of Er₂(SO₄)₃·8H₂O

Abstract

Using the most rigorous approach of direct diagonalization of the Hamiltonian matrix constructed in the complete basis states (364 in number) of the Er3+ ion the observed magnetic susceptibility and anisotropy data of erbium sulphate octahydrate were simulated and the set of crystal field parameters was evaluated. This procedure automatically includes the effect of intermediate coupling and the J-mixing under the crystal field. It was also demonstrated that such rigorous calculation using complete basis states is necessary in order to evaluate the correct set of parameters which may wideJy differ from the values obtained from approximate calculations previousły performed using partial number of basis states of the ion concerned.PACS numbers: 71.70.Ch, 75.10.Dg 1. Introduction The present paper reports the results of simulation of experimental magnetic susceptibility and anisotropy data of Er-sulphate octahydrate by using wave functions which were computed from crystal field theory in the most rigorous way. The crystal fleld (CF) parameters obtained during the process are considered to be accurate ones. For accurate evaluation of any parameter, flrstly it is necessary to evaluate it in a way consistent with all the physical quantities which involve it. Secondly, the most rigorous procedure of calculation of those physical quantities should be followed. Various physical quantities of a rare earth (RE) ion like optical