arXiv subjects

I. Kholbaev

Publications and source records attributed to I. Kholbaev.

3 recordsLinked to original sources

arXiv1998

SQUID nature of microwave absorption in a high-Tc superconducting Ho-Ba-Cu-0 single crystal

A high-Tc, superconducting Ho-Ba-Cu-O single crystal with Tc=86.8 K is investigated on a modified ESR spectrometer at temperatures T>78 K. A signal is observed, whose spectrum in the range of magnetic fields H<0.7 Oe has the form of equivalent absorption lines with an interval Δ= 0.009 Oe. Detailed measurements of the dependence of the spectrum on the amplitude of the microwave field, the temperature, and the orientation of the single crystal are reported. It is established that the absorption spectrum exhibits a typical behavior inherent in SQUIDs with a critical current that decays linearly with increasing T. Three different techniques are used to determine the so-called hysteresis parameter of the postulated SQUID: Li_c /Φ_0 (L and i_c are the inductance and critical current of the SQUID, and Φ_0 is the quantum of magnetic flux). All three techniques give the same result: Li_c (T=79 K)/Φ_0= 3.1\pm 0.3, attesting to the existence of a SQUID-like structure in the single crystal.

cond-mat.supr-con↗

arXiv1998

Magnetically and thermally modulated microwave absorption in Y-Ba-Cu-O single crystal near T_c

The microwave absorption R in the Y-Ba-Cu-O single crystals was investigated near {T_c \approx 92 K} and in the external magnetic field {0<H \leq 9 kOe}. A modified ESR spectrometer was used in the experiment. The method of temperature modulation, along with the usual method of magnetic-field modulation, was first applied in studying of the microwave response of these crystals. Peaks in the temp erature dependencies of the signals {\partial R}/ {\partial H} and {\partial R} /{\partial T} observed in the vicinity of {T_c} were differently shaped and slightly shifted one with respect to another. The evolution of the peaks with variation of the magnetic field and angle θ between {\bf H} and the {\bf c}-axis was traced. It has been shown that the observed difference of the temperature dependencies of the derivatives {\partial R}/{\partial H} and {\partial R}/{\partial T} occures due to the field-induced broadening of the superconducting transition, which is inherent in the high-{T_c} superconductors.

cond-mat↗

arXiv1998

ESR Spectrometry of High-Temperature Superconductors with Temperature-Modulation-Based Thermoregulation

A light-beam-assisted temperature-control system operating within a temperature range from 77 to 180 K is developed for investigating the absorption of electromagnetic waves by high-temperature superconductors in the vicinity of superconducting transition with an ESR spectrometer. The advantage of this system is the feasibility of modulating the temperature of a sample with a frequency of 80 Hz and amplitude of 0.01 -0.1 K. The rms temperature instability over a 5-min time interval is within 0.06 K, the temperature gradient in a sample is 0.01 K/mm for T=90 K, and the system relaxation time is 1 - 10 s. The microwave absorption peaks in the vicinity of the superconducting transition of an Y-Ba-Cu-O, single crystal were first measured at (the simultaneous application of magnetic and temperature modulations.

cond-mat.supr-con↗