Orthorhombic distortion and orbital order in the vanadium spinelFeV2O4

Abstract

Using synchrotron and neutron diffraction measurements, we find a low-temperature orthorhombic phase in vanadium spinel FeV 2 O 4 . The orbital order of V 3+ ions with tetragonal normal modes occurs at 68 K, and this leads to an appearance of the pseudotetragonal phase at a noncollinear ferrimagnetic transition temperature. Below the magnetic transition temperature, unconventional behavior of the orbital state of Fe 2+ ions accompanied by the emergence of the orthorhombic phase was observed by using the normal mode analysis. We have also studied the structural properties of orbitally diluted materials. The orthorhombic phase, which is significantly affected by the other ions, is intrinsic in FeV 2 O 4 . We suggest the orthorhombic phase is strongly related with the double orbital states of Fe 2+ and V 3+ ions.

Oxygen crystallographic positions in thin films by non-destructive resonant elastic X-ray scattering

“…The lattice constant was calculated by a profile matching analysis: a = 0.845750 (7) nm, consistent with previously reported results (Kawaguchi et al, 2016). Using this value, a Rietveld refinement was carried out, leading to x = 0.262 (2) for the oxygen-atom positions.…”

“…All the parameters, including the lattice parameter and the positions of the cations, were fixed except for the oxygen-atoms positions (x). For this simulation part, structure parameters were taken from the literature (Kawaguchi et al, 2016). For reasons of geometry, x is expected to have a value close to 0.25, and spectra were therefore simulated in the range x:[0.230-0.280].…”

“…One example is magnetically active or ferroelectric oxides, where knowledge of the oxygen positions is needed to explain the arrangement responsible for the material's behavior (Giovannetti et al, 2011;Zhou et al, 2019). Equally, in oxides with orbitally ordered states, locating the oxygen atoms allows one to understand the structural deformations which lead to the orbital order inside the material (Kawaguchi et al, 2016).…”

Electronic states and possible origin of the orbital-glass state in a nearly metallic spinel cobalt vanadate: An x-ray magnetic circular dichroism study

“…1 (c). Therefore, a number of experimental and theoretical studies have been performed on the spinel-type vanadates, particularly on the orbital ordering in AV 2 O 4 , where A = Mg [1], Mn [2][3][4][5][6][7][8], Fe [5,6,9,10], Zn [11,12], and Cd [13,14]. All of them exhibit structural phase transitions from the cubic to a low-symmetry phase with decreasing temperature, and the orbital ordering is usually associated with the structural phase transition.…”

Understanding the correlation between orbital degree of freedom, lattice-striction and magneto-dielectric coupling in ferrimagnetic Mn1.5Cr1.5O4

“…When Td-site is occupied with a magnetic ion (i.e., Mn 2+ ), the additional magnetic interaction between Td-site ion and Oh-site ion results in complex magnetic transitions at low temperatures [21][22][23][24][25][26][27]. Moreover, if the magnetic ion at Td-site also possesses orbital degree of freedom (i.e., Fe 2+ ), the lowtemperature phase transitions become more complicated, and the system usually exhibits multiple structural and magnetic transitions [27][28][29][30][31][32].…”