3 research outputs found
Non-Fermi-Liquid Behavior of Superconducting SnH
We studied chemical interaction of Sn with H by X-ray diffraction methods
at pressures of 180-210 GPa. A previously unknown tetrahydride SnH with a
cubic structure () exhibiting superconducting properties below
= 72 K was obtained; the formation of a high molecular -SnH
superhydride and several lower hydrides, SnH and
-SnH, was also detected. The temperature dependence of
critical current density (T) in SnH yields the superconducting gap
2(0) = 20-22 meV at 180 GPa. The SnH superconductor has unusual
behavior in strong magnetic fields: linear temperature dependences of
magnetoresistance and the upper critical magnetic field (T)
( - ). The latter contradicts the
Wertheimer-Helfand-Hohenberg model developed for conventional superconductors.
Along with this, the temperature dependence of electrical resistance of
SnH in normal resistivity state exhibits a deviation from what is expected
for phonon-mediated scattering described by the Bloch-Gr\"uneisen model, and is
beyond the framework of the Fermi liquid theory. Such anomalies occur for many
superhydrides, making them much closer to cuprates than previously believed
Crystal Structure Dynamics of RFe<sub>3</sub>(BO<sub>3</sub>)<sub>4</sub> Single Crystals in the Temperature Range 25–500 K
The multiferroic RFe3(BO3)4 family is characterized by diverse magnetic, magnetoelectric, and magnetoelastic properties, the fundamental aspects of which are essential for modern electronics. The present research, using single-crystal X-ray diffraction (XRD) and Mössbauer spectroscopy (MS) in the temperature range of 25–500 K, aimed to analyze the influence of local atomic coordination on magnetoelectric properties and exchange and super-exchange interactions in RFe3(BO3)4. Low-temperature, single-crystal XRD data of the magnetically ordered phase of RFe3(BO3)4 at 25 K, which were obtained for the first time, were supplemented with data obtained at higher temperatures, making it possible to draw conclusions about the mechanism of the structural dynamics. It was shown that, in structures with R = Gd, Ho, and Y (low-temperature space group P3121), a shift in oxygen atoms (O2, second coordination sphere of R atoms) was accompanied by rotation of the B2O3 triangle toward R atoms at low temperatures, and by different rearrangements in iron chains of two types, in contrast to Nd and Sm iron borates (space group R32). These rearrangements in the structures of space group P3121 affected the exchange and super-exchange paths at low temperatures. The MS results confirm the influence of the distant environment of atoms on the magnetoelectric properties of rare-earth iron borates at low temperatures