Magnetic and structural phase transitions of normal-type spinel ZnCr2Se4 have been studied as functions of applied magnetic field and temperature by means of neutron diffraction. It is found that the spiral spin order of Cr3+ ions is largely affected by the magnetic field, and the satellite-like magnetic reflections are largely decreased in the magnetic field of 0.6 T < H < 1.2 T and disappear at H ≥ 1.2 T, when the magnetic field was applied vertically to an orthorhombic axis . This means that the spiral configuration of the ferromagnetic CrSe4 chains is perfectly disordered around two-fold screw axes in an orthorhombic symmetry phase (Fddd structure) by the magnetic field H ≥ 1.2 T, though the structural phase transition (Tc) between cubic and orthorhombic symmetry phases simultaneously occurs at the antiferromagnetic phase transition temperature (TN ≈ 21 K) in no magnetic field. It is also found that the main reflections show a magnetic field dependence similar to that of the magnetic reflections. Pseudo-tetragonal displacements of Se ions below TN are modulated by the applied magnetic field. The 3 T magnetic field induces a metastable structural transition at about 15 K, after initially cooling down to about 2 K in no applied magnetic field. The transition is related to the modulation from pseudo-tetragonal to pseudo-cubic displacements of Se ions.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics