Manifestation of the Jahn-Teller effect in the EPR spectrum of the metalorganic complex [Cu(en)2H{sub}2O]SO{sub}4

摘要

The temperature dependence of the resonance spectrum of [Cu(en)2H{sub}2O]SO{sub}4 single crystals is investigated in the temperature range 2.3-60 K at a frequency of ～73 GHz. At a temperature T> 15 K the angular dependence of the spectrum is described by a spin Hamiltonian of axial symmetry. At T< 15 K a lowering of the symmetry to rhombic and a splitting the resonance line for a field orientation H‖b are observed. These effects are discussed in a model of two nonequivalent Jahn-Teller centers with intercoupled dynamic distortions in the cell. The low-temperature behavior of the resonance line is due to critical broadening in the region of short-range magnetic order.