  Electronic structure, electrical transport, dc and ac magnetization
properties of the hole substituted (Sr2+) partially B-site disordered double
perovskite Pr2-xSrxCoMnO6 system have been investigated. Electronic structure
was probed by employing X-ray photoemission spectroscopy (XPS) measurements.
The study suggested the presence of mixed valence states of the B-site ions
(Co2+/Co3+ and Mn3+/Mn4+) with significant enhancement of the average oxidation
states due to hole doping. The mere absence of electronic states near the Fermi
level in the valence band (VB) spectra for both of the pure (x=0.0) and Sr
doped (x=0.5) systems indicated the insulating nature of the samples. Sr
substitution is observed to increase the spectral weight near the Fermi level
suggesting for an enhanced conductivity of the hole doped system. The
temperature variation of electrical resistivity measurements revealed the
insulating nature for both the systems, thus supporting the VB spectra results.
The dc magnetization data divulged a Griffiths like phase above the long range
ordering temperature. A typical re-entrant spin glass like phase driven by the
inherent anti-site disorder (ASD) has been maidenly recognized by ac
susceptibility study for both the pure and doped systems. Most interestingly,
the emergence of a new cluster glass like phase (immediately below the magnetic
ordering temperature and above the spin-glass transition temperature) solely
driven by the Sr substitution has been unravelled by ac magnetization dynamics
study. The isothermal magnetization measurements further probed the exhibition
of the giant exchange bias effect emanated from the existence of multiple
magnetic phases.
