Electron paramagnetic resonance studies on multiferroic DyMnO₃ and Dy_0.5Sr_0.5MnO₃

Abstract

Electron paramagnetic resonance (EPR) studies and magnetic measurements were carried out on single crystals of multiferroic DyMnO₃ in hexagonal as well as orthorhombic structures. The interesting effect of strontium dilution on the frustrated antiferromagnetism of DyMnO₃ is also probed using EPR. The line shapes are fitted to broad Lorentzian in the case of pure DyMnO₃ and to modified Dysonian in the case of Dy_0.5Sr_0.5MnO₃. The linewidth, integrated intensity, and geff derived from the signals are analyzed as a function of temperature. The results of magnetization measurements corroborate with EPR results. Our study clearly reveals the signature of frustrated magnetism in pure DyMnO₃ systems. It is found that antiferromagnetic correlations in these systems persist even above the transition. Moreover, a spin-glass-like behavior in Dy_0.5Sr_0.5MnO₃ is indicated by a steplike feature in the EPR signals at low fields.