arXiv subjects

Y. Vaskivskyi

Publications and source records attributed to Y. Vaskivskyi.

3 recordsLinked to original sources

arXiv2026

Room-temperature memristive switching between charge density wave states

Control over charge density wave (CDW) states is technologically promising for the development of ultra-efficient memory devices. However, using electrical pulses for non-volatile resistance switching involving CDW states has so far been limited to cryogenic temperatures. In this work, we investigate a recently discovered layered semiconductor EuTe4, which exhibits the coexistence of distinct CDW orders. We report that electrical pulses can be used for excitation to non-equilibrium, yet stable electronic states across a broad temperature range from 6 K to 400 K. We find that switching occurs through a non-thermal pathway and is reversible via a thermal erase procedure. The resistance of the new electronic state is tunable by the pulse voltage, so the device acts as a memristor. Calculations show fixed bilayer CDW, whereas CDW in single layers shows bistability due to weak Eu-Te links. Low-voltage, fast, and energy-efficient CDW switching holds potential for memristor applications.

cond-mat.mtrl-sci↗

arXiv2024

From domain walls and the stripe phase to full suppression of charge density wave in the superconducting 1T-Ti$_{1-\text{x}}$Ta$_\text{x}$Se$_2$

1T-TiSe$_2$ hosts a $2 \times 2 \times 2$ charge density wave (CDW) that is known to form the state with localized domains separated by the domain walls upon Cu intercalation. The CDW state with the domain wall network has attracted significant interest due to its coexistence with superconductivity. Here we present a scanning tunneling microscopy, transport and magnetic susceptibility study of 1T-Ti$_{1-\text{x}}$Ta$_\text{x}$Se$_2$. Ta substitution for Ti atoms allows us to perform experiments over the wide range of doping ($ 0 \leqslant \text{x} \leqslant 0.2$), providing access to a significantly broader phase diagram than Cu intercalation experiments. At x = 0.02, we observe a complex network of domains and domain walls. We identify two distinct types of domain walls and show their structure with atomic resolution. Additionally, an elusive symmetry-breaking stripe CDW is found at the light substitution of x = 0.02. We also measure highly substituted x = 0.2 crystals that are superconducting despite the full collapse of the CDW order. Our results uncover rich CDW physics in Ta-substituted 1T-TiSe2 crystals and illuminate the interplay between the CDW and superconductivity.

cond-mat.str-el↗

arXiv2021

First-order kinetics bottleneck during photoinduced ultrafast insulator-metal transition in 3D orbitally-driven Peierls insulator CuIr$_{2}$S$_{4}$

The spinel-structure CuIr$_{2}$S$_{4}$ compound displays a rather unusual orbitally-driven three-dimensional Peierls-like insulator-metal transition. The low-T symmetry-broken insulating state is especially interesting due to the existence of a metastable irradiation-induced disordered weakly conducting state. Here we study intense femtosecond optical pulse irradiation effects by means of the all-optical ultrafast multi-pulse time-resolved spectroscopy. We show that the structural coherence of the low-T broken symmetry state is strongly suppressed on a sub-picosecond timescale above a threshold excitation fluence resulting in a structurally inhomogeneous transient state which persists for several-tens of picoseconds before reverting to the low-T disordered weakly conducting state. The electronic order shows a transient gap filling at a significantly lower fluence threshold. The data suggest that the photoinduced-transition dynamics to the high-T metallic phase is governed by first-order-transition nucleation kinetics that prevents the complete ultrafast structural transition even when the absorbed energy significantly exceeds the equilibrium enthalpy difference to the high-T metallic phase. In contrast, the dynamically-decoupled electronic order is transiently suppressed on a sub-picosecond timescale rather independently due to a photoinduced Mott transition.

cond-mat.str-el↗