Electronic structure of the copper(II) ion doped in cubic KZnF3

摘要

The absorption and magnetic circular dichroism spectra of 1percnt;ndash;3percnt; copper(II) doped into the cubic perovskite host KZnF3are measured over the temperature range 1.8ndash;300 K. Sharp magnetic dipole allowed transitions2Eg(Ggr;8)rarr;2T2g(Ggr;7,Ggr;8) are observed together with accompanying vibrational fine structure. The spectra are interpreted on the basis of a tetragonally elongated CuF4minus;6ground state geometry which arises from strong Jahnndash;Teller coupling. This results in a statistical distribution of three equivalent elongations which can undergo reorientation on the electron paramagnetic resonance time scale. The Jahnndash;Teller coupling within the2T2gmultiplet is partially quenched by spinndash;orbit coupling and the lowest Kramers doublet Ggr;7has an octahedral geometry, while the higher lying Ggr;8state has a small tetragonal distortion. This system presents an excellent opportunity to study the spectroscopy of the copper(II) ion in a cubic environment.