arXiv subjects

A. V. Pronin

Publications and source records attributed to A. V. Pronin.

41 records · Page 3Linked to original sources

arXiv2001

Determination of the parameters of semiconducting CdF2:In with Schottky barriers from radio-frequency measurements

Physical properties of semiconducting CdF_2 crystals doped with In are determined from measurements of the radio-frequency response of a sample with Schottky barriers at frequencies 10 - 10^6 Hz. The dc conductivity, the activation energy of the amphoteric impurity, and the total concentration of the active In ions in CdF_2 are found through an equivalent-circuit analysis of the frequency dependencies of the sample complex impedance at temperatures from 20 K to 300 K. Kinetic coefficients determining the thermally induced transitions between the deep and the shallow states of the In impurity and the barrier height between these states are obtained from the time-dependent radio-frequency response after illumination of the material. The results on the low-frequency conductivity in CdF_2:In are compared with submillimeter (10^{11} - 10^{12} Hz) measurements and with room-temperature infrared measurements of undoped CdF_2. The low-frequency impedance measurements of semiconductor samples with Schottky barriers are shown to be a good tool for investigation of the physical properties of semiconductors.

cond-mat.mtrl-sci↗

arXiv2001

Optical conductivity and penetration depth in MgB2

The complex conductivity of a MgB2 film has been investigated in the frequency range 4 cm^{-1}< nu < 30 cm^{-1} and for temperatures 2.7 K < T <300 K. The overall temperature dependence of both components of the complex conductivity is reminiscent of BCS-type behavior, although a detailed analysis reveals a number of discrepancies. No characteristic feature of the isotropic BCS gap temperature evolution is observed in the conductivity spectra in the superconducting state. A peak in the temperature dependence of the real part of the conductivity is detected for frequencies below 9 cm^{-1}. The superconducting penetration depth follows a T^2 behavior at low temperatures.

cond-mat.supr-con↗

arXiv2000

Anisotropic conductivity of Nd_{1.85}Ce_{0.15}CuO_{4-δ} films at submillimeter wavelengths

The anisotropic conductivity of thin Nd$_{1.85}$Ce$_{0.15}$CuO$_{4-δ}$ films was measured in the frequency range 8 cm$^{-1}<ν<$ 40 cm$^{-1}$ and for temperatures 4 K $<T<300$ K. A tilted sample geometry allowed to extract both, in-plane and c-axis properties. The in-plane quasiparticle scattering rate remains unchanged as the sample becomes superconducting. The temperature dependence of the in-plane conductivity is reasonably well described using the Born limit for a d-wave superconductor. Below $T_{{\rm C}%}$ the c-axis dielectric constant $ε_{1c}$ changes sign at the screened c-axis plasma frequency. The temperature dependence of the c-axis conductivity closely follows the linear in T behavior within the plane.

cond-mat.supr-con↗

arXiv2000

Submillimeter spectroscopy of tilted Nd_{1.85}Ce_{0.15}CuO_{4-δ} films: observation of a mixed a-c excitation

The anisotropic conductivity of a series of tilted Nd_{1.85}Ce_{0.15}CuO_{4-δ} thin films was measured by quasioptical spectroscopy in the frequency range 3cm^{-1}<ν<40cm^{-1}. Two characteristic features have been observed in the low-temperature transmission spectra. The first one at ν= 12cm^{-1} was shown to reflect the c-axis plasma frequency of Nd_{1.85}Ce_{0.15}CuO_{4-δ}. The second feature represents a new mixed ab-plane/c-axis excitation. The frequency of this resonance may be changed in a controllable way by rotating the polarization of the incident radiation.

cond-mat.supr-con↗

arXiv1999

Universal relationship between the penetration depth and the normal-state conductivity in YBaCuO

The absolute values of the conductivity in the normal state sigma_n and of the low temperature penetration depths lambda(0) were measured for a number of different samples of the YBaCuO family. We found a striking correlation between sigma_n and 1/lambda^2, regardless of doping, oxygen reduction or defects, thus providing a simple method to predict the superconducting penetration depth and to have an estimate of the sample quality by measuring the normal-state conductivity.

cond-mat.supr-con↗