B-Site Disorder and Spin States Driven Multiple-Magnetic Phases: Griffiths Phase, Re-Entrant Cluster Glass and Exchange Bias in Pr 2 CoFeO 6

The magnetic spin ordering and the magnetization dynamics of a double perovskite Pr2CoFeO6 have been investigated by employing the (dc and ac) magnetization, neutron powder diffraction (NPD) and X-ray magnetic circular dichroism (XMCD) techniques. Structural study revealed that Pr2CoFeO6 adopts a B-site disordered orthorhombic structure (Pnma). Furthermore, ab initio band structure calculations suggested an insulating anti-ferromagnetic ground state. Magnetization measurements revealed the system to possess a spectrum of competing magnetic phases viz., long range antiferromagnetic (canted) spin ordering (TN ~269 K), Griffiths phase, re-entrant cluster glass (RCG) (TG ~34 K) and exchange bias effects. The Neutron diffraction divulged the exhibition of a long range canted G-type spin ordering by Fe spins. Moreover, the electronic structure probed by the X-ray absorption spectroscopy (XAS) study suggested a nominal valance state of +3 for both the B-site ions (Co/Fe). The random non-magnetic dilution of magnetic Fe3+ (HS) ions by Co3+ (LS) ions due to B-site disorder essentially played a crucial role in manifesting the magnetic properties of the system.