Pressure-induced structural phase transition and new superconducting phase in UTe2

We report on the crystal structure and electronic properties of the heavy fermion superconductor UTe2 at high pressure up to 11 GPa, as investigated by X-ray diffraction and electrical resistivity experiments. The X-ray diffraction measurements under high pressure using a synchrotron light source reveal anisotropic linear compressibility of the unit cell up to 3.5 GPa, while a pressure-induced structural phase transition is observed above 3.5-4GPa at room temperature, where the body-centered orthorhombic crystal structure with the space group Immm changes into a body-centered tetragonal structure with the space group I4/mmm. The molar volume drops abruptly at the critical pressure, while the distance between the first-nearest neighbor of U atoms increases, implying a switch from the heavy electronic states to the weakly correlated electronic states. Surprisingly, a new superconducting phase at pressures higher than 7 GPa was detected at Tsc above 2K with a relatively low upper-critical field, Hc2(0). The resistivity above 3.5GPa, thus, in the high-pressure tetragonal phase, shows a large drop below 230 K, which may also be related to a considerable change from the heavy electronic states to the weakly correlated electronic states.Comment: 11 pages, 9 figure

Stability and Metastability of Li3YCl6 and Li3HoCl6

[EN] Metastable solid electrolytes exhibit superior conductivity compared to stable ones, making them a subject of considerable interest. However, synthesis of the metastable phase is affected by multiple thermodynamic and kinetic parameters, leading to ambiguity in the organization of stability and metastability. In this study, we organized remnant and intermediate metastability based on temperature. The intermediate metastable phase, which is less stable than the temperature-independent stable phase, typically transforms into the stable phase(s) at high temperatures. In contrast, the remnant metastable phase is formed by first obtaining most stable phase at specific temperatures and then “trapping” it by rapidly changing the temperature. By investigating Li+ conducting chlorides, Li3MCl6 (M = Y and Ho), we demonstrated that heating starting materials to approximately 600 K produced low-temperature Li3MCl6 phase with one formula unit while further heating resulted in high-temperature Li3MCl6 phase with three formula units. Annealing quenched Li3MCl6 at 573 K resulted in a phase transition from the high-temperature to low-temperature phase, indicating that the high-temperature phase was remnant metastable at low temperatures.This research was partially supported by KAKENHI (Grant No. JP20KK0124), JST PRESTO (Grant Nos. JPMJPR21Q2 and JPMJPR21Q8), and Grant-in-Aid for JSPS Fellows (21J11152).N

The valence state of Yb ion in YbInAu2 compound at high pressure determined by x-ray diffraction and x-ray absorption near edge structure measurements

X-ray diffraction patterns and LIII-edge x-ray absorption near edge structure (XANES) spectra of YbInAu2 and LuInAu2 compounds have been measured at high pressure and room temperature using a diamond anvil cell and a synchrotron radiation at SPring-8. YbInAu2 is more compressible at pressures lower than 4 GPa than above it; the evaluated bulk modulus by Birch-type equation of state is 54.7 GPa which is one-half of that of the LuInAu2 (112.5 GPa). The mean valence v¯ of Yb ion in YbInAu2 determined by the XANES measurement is an increasing function of pressure: 2.71(2) at normal pressure and 2.94(2) at 10 GPa. The rate of increase in v¯ with pressure is two times larger at pressures below 4 GPa than that above 4 GPa. However, the v¯ is described by a linear increasing function of the lattice compression: v¯ =v¯0+2.9|ΔV/V0| where v¯0 is 2.71. The extrapolation to the trivalent state gives the critical pressure of 13 GPa

X-ray magnetic circular dichroism study of the decoupling of the magnetic ordering of the Er and Co sublattices in Er1-xYxCo2 systems

We present an x-ray magnetic circular dichroism (XMCD) study performed at the Co K edge and at the Er L2,3 edges in the Er1-xYxCo2 series. Our results indicate that both Er and Co magnetic sublattices order at the same temperature for all the investigated compounds. In the case of the Er0.6Y0.4Co2 compounds, XMCD data do not show the decoupling of the magnetic ordering for both Er and Co sublattices. Moreover, no experimental evidence of the occurrence of an inverse itinerant electron metamagnetism has been found for applied magnetic fields of up to μ0H=10 T. In addition, a nonzero magnetic moment is found at the Co sites in the case of the Er0.5Y0.5Co2 compound

Revealing Fe magnetism in lanthanide-iron intermetallic compounds by tuning the rare-earth L2,3-edge x-ray absorption edges

We present a systematic x-ray magnetic circular dichroism (XMCD) study performed at the rare-earth L2,3 edges in R(Al1-xFex)2 Laves phase compounds. The progressive substitution of Al by Fe reveals the existence of a non-negligible contribution of Fe to the rare-earth XMCD spectra. This contribution has been isolated and shown to be similar to the dichroic spectrum recorded at the Fe K edge. These results open the possibility of monitoring the Fe magnetism in lanthanides-iron intermetallic compounds by probing the rare-earth L2,3-edge x-ray absorption edges

High-Pressure-Hydrogen-Induced Spin Reconfiguration in GdFe2 Observed by 57Fe-Polarized Synchrotron Radiation Mössbauer Spectroscopy with Nuclear Bragg Monochromator

57Fe-polarized synchrotron radiation Mössbauer spectroscopy (PSRMS) with an X-ray phase plate and a nuclear Bragg monochromator was used to study ferrimagnetic GdFe 2 in high-pressure hydrogen. The pressure-dependent spectraclearly showed a two-step magnetic transition of GdFe2. 57Fe-PSRMS with circular polarization gave direct evidence that the Fe moment was directed parallel to the net magnetization of the GdFe2 hydride at 20 GPa. This spin configuration was opposite to that of the initial GdFe2 , suggesting an extreme weakening of the antiferromagnetic interaction between Fe and Gd. 57Fe-PSRMS enables the characterization of the nonuniform properties of iron-based polycrystalline powder alloys. The excellent applicability of 57Fe-PSRMS covers a wide range of scientific fields

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Pulmonary artery dysfunction in chronic thromboembolic pulmonary hypertension

Background: Unresolved thromboemboli in the pulmonary arteries (PA) is known to cause chronic thromboembolic pulmonary hypertension (CTEPH). However, it remains unknown if vascular dysfunction in pulmonary arteries exists in patients with CTEPH. Methods and results: We enrolled 7 female patients with CTEPH in this study, who have stable pulmonary hemodynamics after balloon pulmonary angioplasty (age; 73.6 ± 3.0 years old, mean right atrial pressure; 4.1 ± 0.4 mm Hg, mean pulmonary arterial pressure; 29.4 ± 2.7, mean pulmonary artery wedge pressure; 8.1 ± 1.2, pulmonary vascular resistance; 397.3 ± 51.7 dynes, cardiac index; 3.1 ± 0.2 L/min/m2). Pulmonary artery vascular function was evaluated by measuring pulmonary artery vasomotion in response to acetylcholine (Ach) at 10-month follow-up after balloon pulmonary angioplasty. All pulmonary vasoactive drugs were discontinued on the day of the procedures. The endothelium-dependent vasomotor response was evaluated by intra-pulmonary artery infusion of Ach at the dose of 10−8 mol/l, and the vaso-spastic response was at 10−6 mol/l. We evaluated vasomotor responses at the same segment in each patient, by measuring % changes of luminal area detected by quantitative pulmonary arterial optical frequency-domain imaging (OFDI), where OFDI catheter was fixed during the procedure. Endothelial dysfunction was observed at the dose of Ach at 10−8 mol/l and vasoconstriction was also confirmed at the dose of Ach at 10−6 mol/l in the diseased pulmonary arteries in CTEPH. Conclusions: These results indicated that the pulmonary artery dysfunction exists in patients with CTEPH, which may be involved in the pathogenesis and progression of CTEPH