Magnetic and Mossbauer Characterization of the Magnetic Properties of Single-Crystalline Sub-Micron Sized Bi2fe4o9 Cubes

Magnetic and Mossbauer characterization of single crystalline, sub-micron sized Bi2Fe4O9 cubes has been performed using SQUID magnetometry and transmission Mossbauer spectroscopy in the temperature range of 4.2 K <= T <= 300 K. A broad magnetic phase transition from the paramagnetic to the anti-ferromagnetic state is observed below 250 K, with the Mossbauer spectra exhibiting a superposition of magnetic, collapsed and quadrupolar spectra in the transition region of 200 K < T < 245 K. Room temperature Mossbauer spectra obtained in transmission geometry are identical to those recorded in back-scattering geometry via conversion electron Mossbauer spectroscopy, indicating the absence of strain at the surface. A small hysteresis loop is observed in SQUID measurements at 5 K, attributable to the presence of weak-ferromagnetism arising from the canting of Fe3+ ion sublattices in the anti-ferromagnetic matrix. (C) 2014 Elsevier B.V. All rights reserved.