arXiv subjects

Viktor V. Kabanov

Publications and source records attributed to Viktor V. Kabanov.

7 recordsLinked to original sources

arXiv2025

Nanocryotron-driven Charge Configuration Memristor

Cryo-computing - both classical and quantum, is severely limited by the absence of a suitable cryo-memory. The challenge both in terms of energy efficiency and speed have been known for decades, but so far conventional technologies have not been able to deliver adequate performance. Here we present a novel non-volatile memory device which incorporates a superconducting nanowire and an all-electronic charge configuration memristor (CCM) based on switching between charge-ordered states in a layered dichalcogenide material. We investigate the time-dynamics and current-voltage characteristics of such a device fabricated using a NbTiN nanowire and a 1T-TaS2 CCM. The observed dynamical response of the device is faithfully reproduced by modelling of the superconducting order parameter showing versatility of application. The inherent ultrahigh energy efficiency and speed of the device, which is compatible with single flux quantum logic, leads to a promising new memory concept for use in cryo-computing and quantum computing peripheral devices.

physics.comp-ph↗

arXiv2019

Theoretical Modeling of the Non-equilibrium Amorphous State in 1T-TaS$_2$

1T-TaS$_2$ is known for it's remarkably complex phase diagram and it's unique long-lived metastable hidden (H) state. Recently, a novel metastable state has been discovered using higher fluences for photoexcitation than in the case of the H state. The state has been dubbed as amorphous (A) due to it's similarity to glass. Expanding on the work of Brazovskii and Karpov, we show that the A state can be successfully modelled with classical interacting polarons on a two-dimensional hexagonal lattice. We have found that the polaron configuration of the A state corresponds to a frustrated screened Coulomb system, where there is no order-disorder phase transition.

cond-mat.str-el↗

arXiv2019

Fabrication of high-temperature quasi-two-dimensional superconductors at the interface of a ferroelectric Ba$_{0.8}$Sr$_{0.2}$TiO$_{3}$ film and an insulating parent compound of La$_{2}$CuO$_{4}$

We report the first observation of superconductivity in heterostructure consisting of an insulating ferroelectric film (Ba$_{0.8}$Sr$_{0.2}$TiO$_3$) grown on an insulating parent compound of La$_2$CuO$_4$ with [001] orientation. The heterostructure was prepared by magnetron sputtering on a non-atomically-flat surface with inhomogeneities of the order of 1-2 nm. The measured superconducting transition temperature T$_c$ is about 30K. We have shown that superconductivity is confined near the interface region. Application of a weak magnetic field perpendicular to the interface leads to the appearance of the finite resistance. That confirms the quasi-two-dimensional nature of the superconductive state. The proposed concept promises ferroelectrically controlled interface superconductivity which offers the possibility of novel design of electronic devices.

cond-mat.supr-con↗

arXiv2019

Configurational Electronic States in Layered Metallic Dichalcogenides

Mesoscopic irregularly ordered and even amorphous self-assembled electronic structures were recently reported in two-dimensional metallic dichalcogenides (TMDs), created and manipulated with short light pulses or by charge injection. Apart from promising new all-electronic memory devices, such states are of great fundamental importance, since such aperiodic states cannot be described in terms of conventional charge-density-wave (CDW) physics. In this paper we address the problem of metastable mesoscopic configurational charge ordering in TMDs with a sparsely filled charged lattice gas model in which electrons are subject only to screened Coulomb repulsion. The model correctly predicts commensurate CDW states corresponding to different TMDs at magic filling fractions $f_m=1/3,1/4,1/9,1/13,1/16$. Doping away from $f_m$ results either in multiple near-degenerate configurational states, or an amorphous state at the correct density observed by scanning tunnelling microscopy. Quantum fluctuations between degenerate states predict a quantum charge liquid at low temperatures, revealing a new generalized viewpoint on both regular, irregular and amorphous charge ordering in transition metal dichalcogenides.

cond-mat.str-el↗

arXiv2018

Ultrafast jamming of electrons into an amorphous entangled state

New emergent states of matter in quantum systems may be created under non-equilibrium conditions if - through many body interactions - its constituents order on a timescale which is shorter than the time required for the system to reach thermal equilibrium. Conventionally non-equilibrium ordering is discussed in terms of symmetry breaking, nonthermal order-disorder, and more recently quenched topological transitions. Here we report a fundamentally new and unusual metastable form of amorphous correlation-localized fermionic matter, which is formed in a new type of quantum transition at low temperature either by short pulse photoexcitation or by electrical charge injection in the transition metal dichalcogenide 1T-TaS2. Scanning tunnelling microscopy (STM) reveals a pseudo-amorphous packing of localized electrons within the crystal lattice that is significantly denser than its hexagonally ordered low-temperature ground state, or any other ordered states of the system. Remarkably, the arrangement is not random, but displays a hyperuniform spatial density distribution commonly encountered in classical jammed systems, showing no signs of aggregation or phase separation. Unexpectedly for a localized electron system, tunnelling spectroscopy and multi- STM-tip surface resistance measurements reveal that the overall state is gapless and conducting, which implies that localized and itinerant carriers are resonantly entangled. The amorphous localized electron subsystem can be understood theoretically to arise from strong correlations between polarons sparsely dispersed on a 2D hexagonal atomic lattice, while itinerant carriers act as a resonantly coupled reservoir distinct in momentum space.

cond-mat.str-el↗

arXiv2004

Dynamic inhomogeneity, pairing and superconductivity in cuprates

In this review we examine the experimental evidence for dynamic inhomogeneity, defining the length, time and energy scales of the relevant elementary excitations. The dynamics of the objects below and above Tc are examined in detail with femtosecond spectroscopy and compared with magnetic and other measurements. The dynamically inhomogeneous state is described theoretically by considering an interaction between electrons, spins and the lattice. By symmetry, only electrons in degenerate states can couple to the lattice and spins to give an anisotropic, d-wave symmetry interaction. The proposed interaction acts on a mesoscopic length-scale, taking into account the interplay of Coulomb repulsion between particles and anisotropic elastic strain, and leads to the formation of bipolaron pairs and stripes. The predicted symmetry breaking associated with pairing and stripe formation are observed in numerous experiments. The phenomenology associated with the co-existence of pairs and clusters (stripes) is found to apply to many different experiments ranging from femtosecond dynamics to transport measurements. Excitations of the system are described quite well in terms of a 2-level system, although we find that a complete description may require a more complicated energy landscape due to presence of mesoscopic objects such as stripes or clusters. The formation of the superconducting state can be understood quantitatively to be the result of the establishment of phase coherence percolation across pairs and stripes.

cond-mat.supr-con↗

arXiv2002

Carrier relaxation dynamics in high temperature superconductors

In this report we review recent experimental results on photoexcited carrier relaxation dynamics on high temperature superconductors (HTSC) probed by a femtosecond time-resolved optical spectroscopy, and compare the results with the data obtained on quasi two dimensional charge density waves. In these experiments, a femtosecond laser pump pulse excites electron-hole pairs via an inter-band transition in the material. These hot carriers rapidly release their energy via electron-electron and electron-phonon collisions reaching states near the Fermi energy within ~100 fs. If an energy gap is present in the low-energy density of states (DOS), it inhibits the final relaxation step and photoexcited carriers accumulate above the gap causing a transient change in reflectivity arising from excited state absorption. The relaxation and recombination processes of photoexcited quasiparticles, governed by the magnitude, anisotropy and the T-dependence of the low energy gap, are monitored by measuring the resulting photoinduced absorption as a function of time after the photoexcitation. This way, the studies of carrier relaxation dynamics give us direct information of the T-dependent changes in the low energy DOS. The technique is particularly useful to probe the systems with spatial inhomogeneities, where different local environments give rise to different relaxation rates. The data on series of HTSC-s show evidence for the coexistence of two distinct relaxation processes, whose T-dependences seem to be governed by two different energy scales: a T-independent pseudogap and a mean-field-like T-dependent gap that opens at Tc. The data suggest the origin of the two-gap behavior is in the intrinsic microscopic spatial inhomogeneity of these materials.

cond-mat.supr-con↗