Investigation of Eu Ternary Pnictide by ESR

The investigation of the ESR in EuZ₂nAs₂ was performed at the frequency 9.3 GHz in the temperature range 4.2 – 300 K. The observed resonance line with the g-factors 1.96 of me Eu²⁺ ions was symmetric and it was described very good by a Lorentzian lineshape at temperatures above 120 K. At the temperature decreasing well before the magnetic ordering temperature (T_N) we was observed an exponential-like increasing of linewidth and a decreasing of the resonance field, indicating the magnification of antiferromagnetic fluctuations and the effective molecular Weis's field. The shape of the resonance line changes from Lorentzian to Gaussian at the temperature close to the T_N. Below TN we observed a decrease of the lineswidth and the changing of the lineshape to the shape close Dysonian.