PROGRESS, PROBLEMY I PERSPEKTIVY KOMNATNO-TEMPERATURNOY SVERKhPROVODIMOSTI
I. A. Troyan, Dmitrii V. Semenok, A. V. Sadakov, I. S. Lyubutin, V. M. Pudalov
Abstract
The discovery of superconductivity at megabar (MB) pressures in hydrogen sulfide H 3 S, followed by metal polyhydrides, starting with binary ones, LaH 10 etc., and ending with ternary ones, including (La,Y)H 10 , has revolutionized the field of condensed matter physics. These discoveries strengthen the hope for solving the century-old problem of creating materials with room-temperature superconductivity. In experiments performed at MB pressures over the past 5 years, besides the synthesis of hydrides, their physical properties were studied using optical, X-ray and Mössbauer spectroscopy methods, as well as galvanomagnetic measurements. We present the main results of galvanomagnetic measurements, including measurements in strong static (up to 21 T) and pulsed (up to 70 T) magnetic fields. Measurements of resistance drop to vanishingly small values at temperatures below the critical T c value, decrease of critical temperature T c with increasing magnetic field, as well as diamagnetic screening indicate the superconducting state of polyhydrides. The results of isotope effect measurements, together with the effect of magnetic impurities on T c , indicate the electron-phonon mechanism of electron pairing. However, interelectron correlations in polyhydrides are by no means small in both superconducting and normal states. Possibly, this is the origin of unusual properties of polyhydrides that have not yet received a satisfactory temperature explanation, such as the linear temperature dependence of the second critical field H c 2 ( T ), linear resistance dependence r( T ), as well as linear magnetoresistance, very similar to that discovered by P. L. Kapitsa in 1929. Article for the special issue of JETP dedicated to the 130th anniversary of P. L. Kapitsa