arXiv subjects

Damjan Svetin

Publications and source records attributed to Damjan Svetin.

8 recordsLinked to original sources

arXiv2026

A programmable superconductor created by light

The quest for superconductivity created by light extends for more than half a century, yet direct evidence of a true zero-resistance state - whose macroscopic quantum phase coherence is both created and controlled by light - has remained elusive. Here we report for the first time on a complex but robust light-programmable superconducting (LiPS) state at an aluminium-silicon heterojunction that is created and fully controlled with femtosecond laser pulses. The superconducting critical temperatures - ranging from 1.8 to 8.5 K, can be increased or erased at will by the application of tailored pulse sequences. At low temperatures the LiPS state shows features characteristic of a Berezinski-Kosterlitz-Thouless topological transition, but another distinct state appears at temperatures above 2 K, which shows clear signatures of quantum phase disorder. In the presence of a magnetic field we observe behaviour characteristic of vortex pinning and creep consistent with the 2-dimensional (2D) nature of the phase coherent system. The origin of the LiPS effect is attributed to light pulse control of the Moire-like superlattice of misfit dislocations (MDs) arising from discommensurations between the Al and Si lattices which is visible by high-resolution electron microscopy. We show how light pulses can be used to control the superlattice periodicity and highlight the appearance of topologically protected soliton-like kinks along the dislocation lines, important for imparting controllable metastability to the system. The demonstration of LiPS paves the way for designing metastable superconducting devices with controllable phase-coherence, enabling applications such as light-engineered quantum circuits, local gap tuning in quantum processors, and optically switchable superconducting devices.

cond-mat.supr-con↗

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↗

arXiv2025

Imaging of electrically controlled van der Waals layer stacking in 1T-TaS2

Van der Waals (vdW) materials exhibit a variety of states that can be switched with low power at low temperatures, offering a viable cryogenic "flash memory" required for the classical control electronics for solid-state quantum information processing. In 1T-TaS2, a non-volatile metallic 'hidden' state can be induced from an insulating equilibrium charge-density wave ground state using either optical or electrical pulses. Given that conventional memristors form localized, filamentary channels which support the current, a key question for design concerns the geometry of the conduction region in highly energy-efficient 1T-TaS2 devices. Here, we report in operando micro-beam X-ray diffraction, fluorescence, and concurrent transport measurements, allowing us to spatially image the non-thermal hidden state induced by electrical switching of 1T-TaS2. Our results reveal a long-range ordered, non-filamentary switched state that extends well below the electrodes, implying that the self-organized, collective growth of the hidden phase is driven by a combination of charge flow and lattice strain. Our unique combination of techniques showcases the potential of non-destructive, three-dimensional X-ray imaging to study bulk switching properties in microscopic detail, namely electrical control of the vdW layer stacking.

cond-mat.str-el↗

arXiv2022

Ultra-Efficient Resistance Switching between Charge Ordered Phases in 1T-TaS$_2$ with a Single Picosecond Electrical Pulse

Progress in high-performance computing demands significant advances in memory technology. Among novel memory technologies that promise efficient device operation on a sub-ns timescale, resistance switching between charge ordered phases of the 1T-TaS$_2$ has shown to be potentially useful for the development of high-speed, energy efficient non-volatile memory device. While ultrafast switching was previously reported with optical pulses, determination of the intrinsic speed limits of actual devices that are triggered by electrical pulses is technically challenging and hitherto still largely unexplored. A new optoelectronic laboratory-on-a-chip, designed for measurements of ultrafast memory switching, enables an accurate measurement of the electrical switching parameters with 100 fs temporal resolution. A photoconductive response is used for ultrashort electrical pulse generation, while its propagation along a coplanar transmission line is detected using electro-optical sampling using a purpose-grown highly-resistive electro-optic (Cd,Mn)Te crystal substrate. By combining the transmission line and the 1T-TaS$_2$ device in a single optoelectronic circuit a non-volatile resistance switching with a single 1.9 ps electrical pulse is demonstrated, with an extremely small switching energy density per unit area E$_A$ = 9.4 fJ/$μ$m$^2$. The experiments demonstrate ultrafast, energy-efficient circuits utilizing switching between non-volatile charge-ordered states offers a new technological platform for cryogenic memory devices.

cond-mat.str-el↗

arXiv2021

Energy efficient manipulation of topologically protected states in non-volatile ultrafast charge configuration memory devices

Non-volatile magnetic storage, from 1940s magnetic core to present day racetrack memory and magnetic anisotropy switching devices rely on the metastability of magnetic domains to store information. However, the inherent inefficiency of converting the information-carrying charge current into magnetization switching sets fundamental limitations in energy consumption. Other non-magnetic non-volatile memories such as memristors, ferroelectric memory and phase change memory devices also rely on energetically relatively costly crystal structural rearrangements to store information. In contrast, conventional electronic charge states in quantum dots for example, can be switched in femtoseconds with high efficiency, but any stored information dissipates rapidly. Here we present a radically different approach in the form of a charge-configuration memory (CCM) device that relies on charge-injection-driven electronic crystal melting and topological protection of the resulting electronic domain configurations of a two-dimensional electronic crystal to store information. With multiprobe scanning tunneling microscopy (STM) we show microscopically, within an operational device, how dislocations in the domain ordering lead to metastability by a mechanism that is topologically equivalent to magnetic bubble memory. The devices have a very small switching energy (<2.2 fJ/bit), ultrafast switching speed of <11 ps and operational range over more than 3 orders of magnitude in temperature (<250 mK ~ 190 K). Together with their simple functionality, a large resistance switching ratio, straightforward fabrication and impressive endurance, CCM devices introduce a new memory paradigm in emerging cryo-computing and other high-performance computing applications that require ultrahigh speed and low energy consumption.

cond-mat.str-el↗

arXiv2019

Unveiling the electronic transformations in the semi-metallic correlated-electron transitional oxide Mo$_8$O$_{23}$

Mo$_8$O$_{23}$ is a low-dimensional chemically robust transition metal oxide coming from a prospective family of functional materials, MoO$_{3-x}$, ranging from a wide gap insulator $(x=0)$ to a metal $(x=1)$. The large number of stoichometric compounds with intermediate $x$ have widely different properties. In Mo$_8$O$_{23}$, an unusual charge density wave transition has been suggested to occur above room temperature, but its low temperature behaviour is particularly enigmatic. We present a comprehensive experimental study of the electronic structure associated with various ordering phenomena in this compound, complemented by theory. Density-functional theory (DFT) calculations reveal a cross-over from a semi-metal with vanishing band overlap to narrow-gap semiconductor behaviour with decreasing temperature. A buried Dirac crossing at the zone boundary is confirmed by angle-resolved photoemission spectroscopy (ARPES). Tunnelling spectroscopy (STS) reveals a gradual gap opening corresponding to a metal-to-insulator transition at 343 K in resistivity, consistent with CDW formation and DFT results, but with large non-thermal smearing of the spectra implying strong carrier scattering. At low temperatures, the CDW picture is negated by the observation of a metallic Hall contribution, a non-trivial gap structure in STS below $\sim 170$ K and ARPES spectra, that together represent evidence for the onset of the correlated state at $70$ K and the rapid increase of gap size below $\sim 30$ K. The intricate interplay between electronic correlations and the presence of multiple narrow bands near the Fermi level set the stage for metastability and suggest suitability for memristor applications.

cond-mat.str-el↗

arXiv2016

Three-dimensional resistivity switching between correlated electronic states in 1T-TaS2

Recent demonstrations of controlled switching between different ordered macroscopic states by impulsive electromagnetic perturbations in complex materials have opened some fundamental questions on the mechanisms responsible for such remarkable behavior. Here we experimentally address the question of whether two-dimensional (2D) Mott physics can be responsible for unusual switching between states of different electronic order in the layered dichalcogenide 1T-TaS2, or it is a result of subtle inter-layer orbitronic re-ordering of its helical stacking structure. We report on the switching properties both in-plane and perpendicular to the layers by current-pulse injection, the anisotropy of electronic transport in the commensurate ground state, and relaxation properties of the switched metastable state. Contrary to recent theoretical calculations, which predict a uni-directional metal perpendicular to the layers, we observe a large resistivity in this direction, with a temperature-dependent anisotropy. Remarkably, large resistance ratios are observed in the memristive switching both in-plane (IP) and out-of-plane (OP). The relaxation dynamics of the metastable state for both IP and OP electron transport are seemingly governed by the same mesoscopic quantum re-ordering process. We conclude that 1T-TaS2 shows resistance switching arising from an interplay of both IP and OP correlations.

cond-mat.mes-hall↗

arXiv2014

The effect of strain on the thawing of the hidden state and other transitions in 1T-TaS2

We investigate the effect of 2-dimensional (in-plane) strain on the critical transition temperature TH from the photoexcited hidden state in 1T-TaS$_2$ thin films on different substrates. We also measure the effect of in-plane strain on the transition temperature $T_{c2}$ between the nearly commensurate charge-density wave state and the commensurate state near 200 K. In each case, the strain is caused by the differential contraction of the sample and the substrate, and ranges from 0.5 % compressive strain (CaF$_2$) to 2 % tensile strain (sapphire). Strain appears to have an opposite effect on the H state and the NC-C state transitions. TH shows a large and negative strain coefficient of dT$_H$/de = - 8900+/-500 K, while $T_{c2}$ is not strongly affected by tensile strain and shows a positive coefficient for compressive strain, which is opposite to the effect observed for hydrostatic pressure.

cond-mat.mtrl-sci↗