L. N. Zherikhina

Increase in the magnetization loop width in the Ba0.6K0.4BiO3 superconductor: Possible manifestation of phase separation

The magnetization of Ba0.6K0.4BiO3 samples in fields up to 90 kOe in the temperature range from 2 to 30 K is investigated. It is shown that the observed increase in the width of the magnetization loop can be explained by a decrease in the phase nonuniformity upon an increase in the magnetic field. The asymmetric hysteretic dependence of magnetization with the secondary peak was successfully described by the extended critical state model taking into account the phase separation in the superconductor.

Self-consistent spatially inhomogeneous state in HTSC Ba1-x KxBiO3 single crystals

A spatially inhomogeneous state in HTSC Ba1-xKxBiO3 single crystals (Tc ≈ 30 K, x = 0.4) has been studied at T < Ť ≈ 17 K, where Ť is the temperature of separation into superconducting and dielectric phases. This separation has earlier been detected in Ba1-xKxBiO3 polycrystals. In the single crystals, the main results are obtained from hysteretic magnetization reversal curves, whereas the character of separation in the polycrystals is clearly visible from I–V curves. The results obtained support the theoretical model of HTSC separation proposed in [1].

The anomalous magnetic properties of high-TC Ba–K–Bi–O in superconducting state

Abstract The magnetic response of HTSC Ba–K–Bi–O single crystals in superconducting state was investigated with the help of a small Hall detector. The magnetic moment of the sample was measured as a function of the magnetic field up to 650 Oe and as a function of temperature while heating in the external magnetic field. Distinct paramagnetic response (PMR) was observed. In contrast to the other works where “paramagnetic Meissner effect” was noted these experiments were carried out on zero field cooled samples and the paramagnetic response was exhibited both at very low (

Observation of latent coherent effects in randomized systems

Coherent interference effects of the following three types are experimentally discovered in disordered (randomized) systems: (i) Josephson behavior of the HTSC polycrystal BaKBiO in the phase-separated state; (ii) oscillations of bismuth film resistance, which are periodic in “direct” magnetic field; and (iii) mesoscopic oscillations of the resistance in the course of film growth. In the first case, the method for detecting the “latent” nonstationary Josephson effect is substantiated by the frequency modulation method for microwave radiation, while in the other two cases, simple models are proposed to explain the nature of coherent oscillations of the resistance. The analogy between the observed oscillations and the Josephson effect in randomized systems is discussed.

H–T phase diagram of high-Tc Ba–K–Bi–O

Abstract The magnetic behavior of Ba–K–Bi–O single crystals below T c was investigated. The magnetic moment hysteresis loops were examined with the help of a small Hall detector. The complex analysis of the data on the temperature dependencies of the residual magnetic moment and H c1 , obtained from the magnetic experiments, and the resistive superconducting transition curves give rise to the following picture: at T c =30 K the transition to the continuous superconducting phase takes place, while at T * =17 K one more transition happens––to the spatially inhomogeneous superconductor–insulator state, that also could be destroyed either by temperature or by magnetic field.

Josephson Fourier spectrometer based on HTSC: Construction and the problem of physical implementation of a quantum computer

The possibility of developing the broadband Fourier spectrometer based on the unsteady Josephson effect in HTSC, with a frequency range including the terahertz region, is considered. A simple design of a precisely tuned point Josephson junction is developed, which allows “fitting” of its parameters immediately under cryogenic conditions. A modification of such a spectrometer for solving the problems of factorizing multidigit numbers is proposed, which is currently one of the best known motivations of works on the quantum computer development.

On the possibility of detecting low-energy scalar and pseudo-scalar bosons

The properties of the conversion of “cold” extra-light scalar or pseudo-scalar bosons weakly interacting with material media to photons with energies of 0.001–1.0 meV are analyzed. Various possible experimental schemes including closed resonant cells at low temperatures and highly sensitive receivers of radio-frequency photons are presented. The existence of such elementary particles is predicted in various expansion versions of the “standard model”. Their direct or indirect detection would make it possible to clarify the nature of the “dark matter” phenomenon.

Ordinary SQUID interferometers and superfluid helium matter wave interferometers: The role of quantum fluctuations

When comparing the operation of a superfluid helium matter wave quantum interferometer (He SQUID) with that of an ordinary direct-current quantum interferometer (dc SQUID), we estimate their resolution limitation that correspond to quantum fluctuations. An alternative mode of operation of the interferometer as a unified macroquantum system is considered.

The new method of frequency modulated microwave field to observe Josephson behavior of the weak links system

Abstract The method of frequency modulation of microwave radiation to observe Josephson behavior of multicircuit weak links system is suggested. The possibilities of the method are theoretically analyzed for the case of the system consisting of many Josephson contacts with random parameters. The technique was sampled on the example of polycrystalline high-T c Ba 0.6 K 0.4 BiO 3 .