  The structural and magnetic properties of double perovskiteTb2CoMnO6 have
been investigated. Electronic structure analysis by XPS study reveals the
presence of mixed oxidation state (Mn4+/Mn3+ and Co2+/Co3+) of B-site ions. The
dc and ac magnetization measurements reveal different interesting phases such
as Griffith phase, re-entrant spin glass, metamagnetic steps, Hopkinson like
peak and also unusual slow relaxation. The M-H curve indicates the presence of
competing AFM/FM interactions. The disorder in Tb2CoMnO6 leads to spin
frustration at low temperature giving rise to the re-entrant spin glass.
Moreover, the field-dependent ac susceptibility studies unraveled the presence
of Hopkinson like peak associated with the domain wall motion and the large
anisotropy field. The further study yielded that the relaxation associated with
this peak is unusually slow.
