Related papers: Octahedral rotation instability in Ba$_2$IrO$_4$

We investigate the crystal structure and lattice vibrations of Sr$_2$IrO$_4$ by a combined phonon Raman scattering and x-ray powder diffraction experiment under pressures up to $66$ GPa and room temperature. Density functional theory (DFT)…

We have performed non-resonant x-ray diffraction, resonant soft and hard x-ray magnetic diffraction, soft x-ray absorption and x-ray magnetic circular dichroism measurements to clarify the electronic and magnetic states of the Co3+ ions in…

Group theoretical aspects of the three temperature-dependent and temperature-reversible experimentally observed phase transitions in the KNbO3 crystal (cubic-tetragonal, tetragonal-orthorhombic, orthorhombic-rhombohedral) in the framework…

The B(E2:0_1^+ -> 2_1^+) values of the Ba isotopes (Z=56) exhibit a sharp increase in deformation as the neutron numbers approach the mid-shell value of N=66. This behavior is anomalous because the 2_1^+ level energies are very similar to…

Double perovskites Cs$_2$Au$_2$X$_6$ (X=Cl, Br, I) are prototypical materials that exhibit charge disproportionation of gold into 1+ and 3+ states. It is known that the disproportionation is resolved under high pressures, and this has…

Li2FeSiO4 is an important alternative cathode for next generation Li-ion batteries due to its high theoretical capacity (330 mA h/g). However, its development has faced significant challenges arising from structural complexity and poor…

Resonant x-ray diffraction performed at the $\rm L_{II}$ and $\rm L_{III}$ absorption edges of Ru has been used to investigate the magnetic and orbital ordering in Ca$_2$RuO$_4$ single crystals. A large resonant enhancement due to electric…

An incommensurate modulated structure was found recently in a light group V element phosphorous in the phase P-IV stable in the pressure range 107-137 GPa. We consider configurations of the Brillouin zone and Fermi sphere within a…

Laminar-turbulent transition on a rotating wind turbine blade at a chord Reynolds number of $1 \times 10^5$ and varying angles of attack ($AoA$) is studied with direct numerical simulations and linear stability theory. The rotation effects…

We have investigated structures of the ground and excited states of $^{16}\textrm{O}$ with the method of variation after spin-parity projection in the antisymmetrized molecular dynamics model combined with the generator coordinate method of…

We present the theory of orbital ordering in orbital-degenerate itinerant electron systems. After proposing the criterion of instability for orbital ordering or orbital density wave ordering, we find that the orbital and the spin-orbital…

Recently, the possibility of a low-temperature non-cubic phase in BaZrO$_3$ has generated engaging discussions about its true ground state and the consequences on its physical properties. In this paper, we investigate the microscopic…

We use single-crystal neutron diffraction to determine the crystal structure symmetry and the magnetic evolution in the rhodium doped iridates $\rm Sr_2Ir_{1-x}Rh_{x}O_4$ ($0\leq x \leq 0.16$). Throughout this doping range, the crystal…

Recent theoretical study has shown that the hexagonal YCo$_5$ is dynamically unstable and distorts into a stable orthorhombic structure. In this study, we show theoretically that the orthorhombic phase is energetically more stable than the…

Perovskite ABO$_3$ oxides display an amazing variety of phenomena that can be altered by subtle changes in the chemistry and internal structure, making them a favorite class of materials to explore the rational design of novel properties.…

The list of possible commensurate phases obtained from the parent tetragonal phase of perovskites by allowing the tilting of octahedra of oxygen ions is reexamined. It is found that many structures allowed by symmetry are not consistent…

The structure of dielectric perovskite BaZrO$_3$, long known to be cubic at room temperature without any structural phase transition with variation of temperature, has been recently disputed to have different ground state structures with…

We report high-resolution single-crystal inelastic neutron scattering measurements on the spin-1/2 antiferromagnet Ba(TiO)Cu$_4$(PO$_4$)$_4$. This material is formed from layers of four-site \cupola" structures, oriented alternately upwards…

We present results of an experimental study on single crystals of a 5d1 double perovskite Ba2CaReO6. Magnetization measurements reveal a weak splitting between zero-field-cooled and field-cooled protocols below 12 K. At magnetic fields…

Materials with a 5d4 electronic configuration are generally considered to have a nonmagnetic ground state (J=0). Interestingly, Sr2YIrO6 (Ir5+ having 5d4 electronic configuration) was recently reported to exhibit long-range magnetic order…