Anomalous High-Temperature Superconductivity in YH.

Pressure-stabilized hydrides are a new rapidly growing class of high-temperature superconductors, which is believed to be described within the conventional phonon-mediated mechanism of coupling. Here, the synthesis of one of the best-known high-T superconductors-yttrium hexahydride -YH is reported, which displays a superconducting transition at ≈224 K at 166 GPa. The extrapolated upper critical magnetic field B (0) of YH is surprisingly high: 116-158 T, which is 2-2.

Novel Strongly Correlated Europium Superhydrides.

We conducted a joint experimental-theoretical investigation of the high-pressure chemistry of europium polyhydrides at pressures of 86-130 GPa. We discovered several novel magnetic Eu superhydrides stabilized by anharmonic effects: cubic EuH, hexagonal EuH, and an unexpected cubic (3) clathrate phase, EuH. Monte Carlo simulations indicate that cubic EuH has antiferromagnetic ordering with of up to 24 K, whereas hexagonal EuH and 3-EuH possess ferromagnetic ordering with = 137 and 336 K, respectively.

Pressure Induced Spin Crossover and Magnetic Properties of Multiferroic BaNbFeSiO.

Recently, the iron containing langasite-type crystal BaNbFeSiO has attracted great attention as a new magnetically induced multiferroic. In this work, magnetic, structural and electronic properties of the multiferroic BaNbFeSiO were investigated by several methods, including synchrotron X-ray diffraction, Raman spectroscopy and synchrotron Mössbauer source technique at high quasi-hydrostatic pressures (up to 70 GPa), created in diamond anvil cells. At room temperature, two structural transitions at pressures of about 3.

Observation of superconductivity in hydrogen sulfide from nuclear resonant scattering.

High-temperature superconductivity remains a focus of experimental and theoretical research. Hydrogen sulfide (H2S) has been reported to be superconducting at high pressures and with a high transition temperature. We report on the direct observation of the expulsion of the magnetic field in H2S compressed to 153 gigapascals.

Quantum critical point and spin fluctuations in lower-mantle ferropericlase.

Ferropericlase [(Mg,Fe)O] is one of the most abundant minerals of the earth's lower mantle. The high-spin (HS) to low-spin (LS) transition in the Fe(2+) ions may dramatically alter the physical and chemical properties of (Mg,Fe)O in the deep mantle. To understand the effects of compression on the ground electronic state of iron, electronic and magnetic states of Fe(2+) in (Mg0.

Insulator-metal transition in highly compressed NiO.

The insulator-metal transition was observed experimentally in nickel monoxide (NiO) at very high pressures of ~240 GPa. The sample resistance becomes measurable at about 130 GPa and decreases substantially with the pressure increase to ~240 GPa. A sharp drop in resistance by about 3 orders of magnitude has been observed at ~240 GPa with a concomitant change of the resistance type from semiconducting to metallic.

Single-bonded cubic form of nitrogen.

Nitrogen usually consists of molecules where two atoms are strongly triple-bonded. Here, we report on an allotropic form of nitrogen where all atoms are connected with single covalent bonds, similar to carbon atoms in diamond. The compound was synthesized directly from molecular nitrogen at temperatures above 2,000 K and pressures above 110 GPa using a laser-heated diamond cell.