Spin-glass behavior in amorphous BiFeO3

Abstract

Short-range antiferromagnetic (speromagnetic) behavior was observed for amorphous BiFeO3 by static magnetic measurements, ac susceptibility (χac) measurement, and 57Fe Mössbauer spectra measurements. The magnetic behavior is classified into three temperature ranges: (i) paramagnet for T≳220 K; (ii) local clustering of spins for 20 K<T<220 K; and (iii) speromagnet in which all spins are frozen into random directions for T<20 K. In the spin freezing state the magnetization shows irreversibility and the χac−T curve has a cusp. The variation of the spin freezing temperature against measuring magnetic field and measuring frequency indicate that the speromagnetic order is very similar to that of spin glass.