Magnetic Pseudoresonance in Manganite Thin Films

A strong narrow peak in the field dependence of the radio-frequency absorption (the magnetic pseudoresonance) has been found and investigated in epitaxial thin films of La_2/3Sr_1/3MnO₃ possessing uniaxial magnetic anisotropy in the film plane. The peak is observed when the in-plane external magnetic field H is directed perpendicular to the easy axis and equals to the anisotropy field H _u. The frequency dependence of the peak magnitude measured in the frequency range of 10–300 MHz approximately follows the Debye law behavior with the characteristic relaxation time of about 2.2 ns. The physical model of the phenomenon is suggested, based on the giant increase in static transversal susceptibility due to a sharp reorientation of the equilibrium magnetization when approaching the pseudoresonance conditions.