Related papers: Prolonged mixed phase induced by high pressure in …
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…
Synchrotron X-ray diffraction and Raman spectroscopy have been used to study chemical reactions of molecular hydrogen (H2) with sulfur (S) at high pressures. We find theoretically predicted Cccm and Im-3m H3S to be the reaction products at…
Phase transitions and symmetry are intimately linked. Melting of ice, for example, restores translation invariance. The mysterious hidden order (HO) phase of URu$_2$Si$_2$ has, despite relentless research efforts, kept its symmetry breaking…
The molecular phase of hydrogen converts to the atomic metallic phase at high pressures estimated usually as 300 - 500 GPa. We analyze the decay of metallic phase as the pressure is relieved below the transition one. The metallic state is…
The electrical conductivity and Raman spectroscopy measurements have been performed on MoS$_2$ at high pressures up to 90 GPa and variable temperatures down to 5 K. We find that the temperature dependence of the resistance in a metallic…
A hexagonal structure of solid molecular hydrogen with $P6_122$ symmetry is calculated to be more stable below about 200 GPa than the monoclinic $C2/c$ structure identified previously as the best candidate for phase III. We find that the…
The structure of solid oxygen has been studied at pressures from 50 to 140~GPa using static structure search methods and molecular dynamics simulations with density functional theory and a hybrid exchange functional. Several crystalline…
Pressure-induced superconductivity and structural phase transitions in phosphorous (P) are studied by resistivity measurements under pressures up to 170 GPa and fully $ab-initio$ crystal structure and superconductivity calculations up to…
Based on evolutionary crystal structure searches in combination with ab initio calculations, we predict an unusual structural phase of the superconducting LaH$_{10}$ that is stable from about 250 GPa to 425 GPa pressure. This new phase…
Cooperative Jahn-Teller ordering is well-known to drive the cubic $Fd\overline{3}m$ to tetragonal $I$4$_1$/$amd$ structural distortion in Mn$_3$O$_4$ at 1170 $^{\circ}$C. Further structural distortion occurs in Mn$_3$O$_4$ upon magnetic…
We investigated the evolution of ferromagnetism in layered Fe$_3$GeTe$_2$ flakes under different pressures and temperatures using in situ magnetic circular dichroism (MCD) spectroscopy. We found that the rectangle shape of hysteretic loop…
We investigate the structural and magnetic phase transitions in EuTi1-xNbxO3 with synchrotron powder X-ray diffraction (XRD), resonant ultrasound spectroscopy (RUS), and magnetization measurements. Upon Nb-doping, the Pm-3m to I4/mcm…
Two magnetic ordering transitions are found in InMnO3, the paramagnetic to antiferromagnetic transition near ~118 K and a lower possible spin rotation transition near ~42 K. Multiple length scale structural measurements reveal enhanced…
Transition metal dihalides (MX$_2$, M= transition metal, X= halide) have attracted much attention recently due to their intriguing low-dimensional magnetic properties. Particular focus has been placed in this family in the context of…
The effect of electron doping on the structural, transport, and magnetic properties of Mn (IV) - rich Ca1-xYxMnO3 (x < 0.2) samples have been investigated using neutron diffraction, neutron depolarization, magnetization and resistivity…
Neutron diffraction studies of antiferromagnetic MnO confined to MCM-41 type matrices with channel diameters 24-87 A demonstrate a continuous magnetic phase transition in contrast to a discontinuous first order transition in the bulk. The…
Computational searches for structures of solid oxygen under pressures in the multi TPa range have been carried out using density-functional-theory methods. We find that molecular oxygen persists to about 1.9 TPa at which it transforms into…
We studied the crystal structure of TiOCl up to pressures of $p$=25~GPa at room temperature by x-ray powder diffraction measurements. Two pressure-induced structural phase transitions are observed: At $p_{c1}$$\approx$15~GPa emerges an…
The electron and phonon spectra, as well as the density of electron and phonon states of the stable orthorhombic structure of hydrogen sulfide (SH2) at pressures 100-180 GPa have been calculated. It is found that the set of parallel planes…
We report the temperature dependent x-ray powder diffraction of the quaternary compound NdOFeAs (also called NdFeAsO) in the range between 300 K and 95 K. We have detected the structural phase transition from the tetragonal phase, with…