Electron Spin Resonance Studies of Undoped and Dysprosium Doped Bismuth Ferrite Nanoparticles

The magnetic state of multiferroic Bi (1-x) Dy (x) FeO (3) (where x = 0.0, 0.05) nanoparticles that synthesized by the sol-gel method has been probed by electron spin resonance (ESR) spectroscopy. Systematic analysis of the obtained ESR spectra revealed that the strong signal with asymmetric line shape is due to the cycloidal spin structure in the bismuth ferrite (BFO) system. While the magnetic behaviour of BFO is intriguing with conflicting reports that attribute to its 'spin glass' and 'domain pinning' effects etc., our ESR data of line width temperature independence supports the spin glass scenario. Further, we have observed a dip or minimum with a narrow valley in the temperature dependence of Delta g/g at 75 K for Bi Dy-0.95 0.05FeO (3) (BDFO), indicating an abrupt disruption and decrease of canting spin order at that particular temperature.