arXiv subjects

M. Lyatti

Publications and source records attributed to M. Lyatti.

6 recordsLinked to original sources

arXiv2026

Development and characterization of YBa$_2$Cu$_3$O$_{7-x}$/SrTiO$_3$ nanomembrane platform for silicon photonics integration

Integration of high-temperature superconducting devices with photonic circuits requires a material platform that preserves superconducting properties, provides interfacial heat transport control and optical accessibility. A YBa$_2$Cu$_3$O$_{7-x}$/SrTiO$_3$ (YBCO/STO) nanomembrane platform, enabling integration with SiO$_2$/Si substrates, is developed and characterized. Millimeter-scale ultra-thin YBCO films are grown on a STO/Sr$_{1.5}$Ca$_{1.5}$Al$_2$O$_6$ bilayer, released on a STO nanomembrane, and transferred onto SiO$_2$/Si substrates. X-ray diffraction confirms that crystallinity of STO and YBCO is preserved after transfer. Microbridges patterned from transferred YBCO films exhibit a critical temperature of 88.8 K and a critical current density of 6.8 MA/cm$^2$ at 77 K, comparable with those of YBCO films on STO substrates. Statistical measurements show a device fabrication yield of 93%, a critical-temperature variation of only 0.05 K, and 10% variation in critical current density, demonstrating excellent reproducibility. The thermal boundary conductance across the van der Waals interface between the YBCO/STO platform and the SiO$_2$/Si substrate is strongly reduced compared to that of epitaxial YBCO film on STO substrate. The reduced thermal coupling prolongs nonequilibrium states in superconducting nanostructures, which is advantageous for detector applications. These results establish ultra-thin YBCO films on optically transparent STO nanomembranes as a platform for integrating high-T$_c$ superconducting devices with silicon photonics.

cond-mat.supr-con↗

arXiv2023

In-plane anisotropy of electrical transport in Y$_{0.85}$Tb$_{0.15}$Ba$_2$Cu$_3$O$_{7-x}$ films

We fabricate high-quality c-axis oriented epitaxial YBa$_2$Cu$_3$O$_{7-x}$ films with 15% of yttrium atoms replaced by terbium (YTBCO) and study their electrical properties. The Tb substitution reduces the charge carrier density resulting in increased resistivity and decreased critical current density compared to the pure YBa$_2$Cu$_3$O$_{7-x}$ films. The electrical properties of the YTBCO films show an in-plane anisotropy in both the superconducting and normal state providing evidence for the twin-free film. Unexpectedly, the resistive transition of the bridges also demonstrates the in-plane anisotropy that can be explained within the framework of Tinkham's model of the resistive transition and the Berezinskii-Kosterlitz-Thouless (BKT) model depending on the sample parameters. We consider YTBCO films to be a promising platform for both the fundamental research on the BKT transition in the cuprate superconductors and for the fabrication of devices with high kinetic inductance.

cond-mat.supr-con↗

arXiv2023

Quantum size effects in ultra-thin YBa2Cu3O7-x films

The d-wave symmetry of the order parameter with zero energy gap in nodal directions stands in the way of using high-temperature superconductors for quantum applications. We investigate the symmetry of the order parameter in ultra-thin YBa2Cu3O7-x (YBCO) films by measuring the electrical transport properties of nanowires and nanoconstrictions aligned at different angles relative to the main crystallographic axes. The anisotropy of the nanowire critical current in the nodal and antinodal directions reduces with the decrease in the film thickness. The Andreev reflection spectroscopy shows the presence of a thickness-dependent energy gap that doesn't exist in bulk YBCO. We find that the thickness-dependent energy gap appears due to the quantum size effects in ultra-thin YBCO films that open the superconducting energy gap along the entire Fermi surface. The fully gapped state of the ultra-thin YBCO films makes them a very promising platform for quantum applications, including quantum computing and quantum communications.

cond-mat.supr-con↗

arXiv2019

High-resistance YBa2Cu3O7-x grain-boundary Josephson junctions fabricated by electromigration

[100]-tilt grain-boundary YBa2Cu3O7-x (YBCO) junctions are promising for investigation of macroscopic quantum phenomena in high-Tc Josephson junctions. However, fabrication of the [100]-tilt grain-boundary YBCO junctions with a high resistance, which are required to study quantum effects, is difficult because of a high transparency of a tunnel barrier in this type of junctions. Here, we demonstrate a modification of grain-boundary barrier properties with a new approach to an oxygen electromigration in the YBCO grain-boundary junctions when the oxygen diffuses under an applied electric field from the grain-boundary to a BaTbO3 layer deposited atop of an YBCO film. Using this approach, we changed the normal-state resistance of the junctions from tens to several hundred Ohms without a degradation of their characteristic voltage IcRn and determined a barrier height and thickness by measuring the quasiparticle tunnelling current.

cond-mat.supr-con↗

arXiv2019

Energy-level quantization in YBa2Cu3O7-x phase-slip nanowires

Significant progress has been made in the development of superconducting quantum circuits, however new quantum devices that have longer decoherence times at higher temperatures are urgently required for quantum technologies. Superconducting nanowires with quantum phase slips are promising candidates for use in novel devices that operate on quantum principles. Here, we demonstrate ultra-thin YBa2Cu3O7-x nanowires with phase-slip dynamics and study their switching-current statistics at temperatures below 20 K. We apply theoretical models that were developed for Josephson junctions and show that our results provide strong evidence for energy-level quantization in the nanowires. The crossover temperature to the quantum regime is 12-13 K, while the lifetime in the excited state exceeds 20 ms at 5.4 K. Both values are at least one order of magnitude higher than those in conventional Josephson junctions based on low-temperature superconductors. We also show how the absorption of a single photon changes the phase-slip and quantum state of a nanowire, which is important for the development of single-photon detectors with high operating temperature and superior temporal resolution. Our findings pave the way for a new class of superconducting nanowire devices for quantum sensing and computing.

cond-mat.supr-con↗

arXiv2018

Experimental evidence for hotspot and phase-slip mechanisms of voltage switching in ultra-thin YBa2Cu3O7-x nanowires

We have fabricated ultra-thin YBa2Cu3O7-x nanowires with a high critical current density and studied their voltage switching behavior in the 4.2 - 90 K temperature range. A comparison of our experimental data with theoretical models indicates that, depending on the temperature and nanowire cross section, voltage switching originates from two different mechanisms: hotspot-assisted suppression of the edge barrier by the transport current and the appearance of phase-slip lines in the nanowire. Our observation of hotspot-assisted voltage switching is in good quantitative agreement with predictions based on the Aslamazov-Larkin model for an edge barrier in a wide superconducting bridge.

cond-mat.supr-con↗