  This work reports an exchange bias (EB) effect up to room temperature in the
binary intermetallic bulk compound Mn3.04Ge0.96. The sample annealed at 700 K
crystallizes in a tetragonal structure with ferromagnetic ordering, whereas,
the sample annealed at 1073 K crystallizes in a hexagonal structure with
antiferromagnetic ordering. The hexagonal Mn3.04Ge0.96 sample exhibits an EB of
around 70 mT at 2 K that continues with a non-zero value up to room
temperature. The exchange anisotropy is proposed to be originating from the
exchange interaction between the triangular antiferromagnetic host and the
embedded ferrimagnetic like clusters. The ferrimagnetic clusters develop when
excess Mn atoms occupy empty Ge sites in the original triangular
antiferromagnet structure of Mn3Ge.
