  In-field DC and AC magnetization measurements were carried out on a
sigma-phase Fe55Re45 intermetallic compound aimed at determination of the
magnetic phase diagram in the H-T plane. Field cooled, M_FC, and zero-field
cooled, M_ZFC, DC magnetization curves were measured in the magnetic field, H,
up to 1200 Oe. AC magnetic susceptibility measurements were carried out at a
constant frequency of 1465 Hz under DC fields up to H=500 Oe. The obtained
results provide evidences for re-entrant magnetism in the investigated sample.
The magnetic phase diagrams in the H-T plane have been outlined based on
characteristic temperatures determined from the DC and AC measurements. The
phase diagrams are similar yet not identical. The main difference is that in
the DC diagram constructed there are two cross-over transitions within the
strong-irreversibility spin-glass state, whereas in the AC susceptibility based
diagram only one transition is observed. The border lines (irreversibility,
cross-over) can be described in terms of the power laws.
