65 research outputs found
Role of Sb in the superconducting kagome metal CsV$3Sb5 revealed by its anisotropic compression
Pressure evolution of the superconducting kagome metal CsVSb is
studied with single-crystal x-ray diffraction and density-functional
band-structure calculations. A highly anisotropic compression observed up to 5
GPa is ascribed to the fast shrinkage of the Cs-Sb distances and suppression of
Cs rattling motion. This prevents Sb displacements required to stabilize the
three-dimensional charge-density-wave (CDW) order and elucidates the
disappearance of the CDW already at 2 GPa despite only minor changes in the
electronic structure of the normal state. At higher pressures, vanadium bands
still change only marginally, whereas antimony bands undergo a major
reconstruction caused by the gradual formation of the interlayer Sb-Sb bonds.
Our results exclude pressure tuning of vanadium kagome bands as the main
mechanism for the non-trivial evolution of superconductivity in real-world
kagome metals. Concurrently, we establish the central role of Sb atoms in the
stabilization of a three-dimensional CDW and Fermi surface reconstruction.Comment: published versio
Charge order and suppression of superconductivity in HgBa2CuO4 at high pressures
New insight into the superconducting properties of HgBa2CuO4 (Hg-1201)
cuprates is provided by combined measurements of the electrical resistivity and
single crystal X-ray diffraction under pressure. The changes induced by
increasing pressure up to 20GPa in optimally doped single crystals were
investigated. The resistivity measurements as a function of temperature show a
metallic behavior up to ~10GPa that gradually passes to an insulating state,
typical of charge ordering, that totally suppresses superconductivity above
13GPa. The changes in resistivity are accompanied by the apparition of sharp
Bragg peaks in the X-ray diffraction patterns indicating that the charge
ordering is accompanied by a 3D oxygen ordering appearing at 10GPa of
wavevector [0.25, 0, L]. As pressure induces a charge transfer of about 0.02 at
10GPa, our results are the first observation of charge order competing with
superconductivity that develops in the over-doped region of the phase diagram
of a cuprate.Comment: 9 pages, 3 figure
Stability of the tetragonal phase of BaZrO3 under high pressure
In this paper, we revisit the high pressure behavior of BaZrO3 by a combination of first-principle calculations, Raman spectroscopy and x-ray diffraction under high pressure. We confirm experimentally the cubic-to -tetragonal transition at 10 GPa and find no evidence for any other phase transition up to 45 GPa, the highest pressures investigated, at variance with past reports. We reinvestigate phase stability with density functional theory considering not only the known tetragonal (I4/mcm) phase but also other potential antiferrodistortive candidates. This shows that the tetragonal phase becomes progressively more stable upon increasing pressure as compared to phases with more complex tilt systems. The possibility for a second transition to another tilted phase at higher pressures, and in particular to the very common orthorhombic Pnma structure, is therefore ruled out
Crystals springing into action : metal–organic framework CUK-1 as a pressure-driven molecular spring
Mercury porosimetry and in situ high pressure single crystal X-ray diffraction revealed the wine-rack CUK-1 MOF as a unique crystalline material capable of a fully reversible mechanical pressure-triggered structural contraction. The near-absence of hysteresis upon cycling exhibited by this robust MOF, akin to an ideal molecular spring, is associated with a constant work energy storage capacity of 40 J g(-1). Molecular simulations were further deployed to uncover the free-energy landscape behind this unprecedented pressure-responsive phenomenon in the area of compliant hybrid porous materials. This discovery is of utmost importance from the perspective of instant energy storage and delivery
Îş-(BEDT-TTF)2Cu2(CN)3 spin liquid : beyond the average structure
We present here the first accurate determination of the exact structure of Îş-(BEDT-TTF)2Cu2(CN)3. Not only did we show that the room temperature structure used over the last twenty years was incorrect, but we were also able to correctly and precisely determine it. The results of our work provide evidence that the structure presents a triclinic symmetry with two non-equivalent dimers in the unit cell, which implies a charge disproportionation between the dimers. However, structural refinement shows that the charge disproportionation is quite weak at room temperature
Cationic and Anionic Disorder in CZTSSe Kesterite Compounds: A Chemical Crystallography Study
International audienc
Giant Nernst effect in the incommensurate charge density wave state of P4W12O44
International audienceWe report the study of Nernst effect in quasi-low-dimensional tungsten bronze P4W12O44 showing a sequence of Peierls instabilities. We demonstrate that both condensation of the electronic carriers in the charge density wave state and the existence of high-mobility electrons and holes originating from the small pockets remaining in the incompletely nested Fermi surface give rise to a Nernst effect of a magnitude similar to that observed in heavy fermion compounds
Two polymorphs of a syn-facial [Tricarbonyl(6; 1-benzyl) chromium] manganese tricarbonyl complex. A shorter Cr-Mn distance induced from the crystal packing ?
International audienc
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