Detailed study of the magnetic ordering in FeMnP0.75Si0.25

• Magnetic and crystallographic properties of FeMnP0.75Si0.25 have been investigated.
• Co-existing ferro- and antiferromagnetic ordering arise from two phases of Fe2P-type.
• A low temperature incommensurate antiferromagnetic structure is revealed.

Magnetic and crystallographic properties of FeMnP0.75Si0.25 in the hexagonal Fe2P-type structure have been investigated by X-ray powder diffraction, neutron powder diffraction and magnetic measurements. The room temperature diffractograms reveal co-existence of two distinct structural phases in the samples with small, but significant, differences only in the unit cell dimensions. The volume ratio between the two phases is governed by the annealing conditions. One of the phases orders ferromagnetically (TC=250 K) and the other in an incommensurate antiferromagnetic structure at low temperatures (qx=0.363(1)qx=0.363(1), TN=150 K).

The ferromagnetic structure of sample I (a) and the antiferromagnetic and incommensurate (qx=0.363(1)qx=0.363(1)) low temperature structure of sample II (b). The magnetic moments of the Mn and Fe atoms in (b) are aligned in the basal plane along the a- and the b-axis, respectively, and the amplitude of the moments propagates sinusoidally along the a-axis.Figure optionsDownload as PowerPoint slide