arXiv subjects

Tatyana Bendikov

Publications and source records attributed to Tatyana Bendikov.

4 recordsLinked to original sources

arXiv2026

Sensing single molecule magnets with nitrogen vacancy centers

Single-molecule magnets (SMMs) are molecules that can function as nanoscale magnets with potential use as magnetic memory bits. While SMMs can retain magnetization at low temperatures, characterizing them on surface and at room temperature remains challenging and requires specialized nanoscale techniques. Here, we use single nitrogen-vacancy (NV) centers in diamond as highly sensitive, broadband magnetic field sensors to detect the magnetic noise of cobalt-based SMMs deposited on a diamond surface. We measure the NV relaxation and decoherence times at 296 K and at 5-8 K, observing a significant influence of the SMMs on them. From this, we can infer the SMMs' magnetic noise spectral density (NSD) and underlying magnetic properties. Moreover, we observe the effect of an applied magnetic field on the SMMs' NSD at low temperatures. The method provides nanoscale sensitivity for characterizing SMMs under realistic conditions relevant to their use as surface-bound memory units.

quant-ph↗

arXiv2025

Protein-Based Electrical Junctions with Robust Biocompatible Carbon Electrodes Exhibit Activation-less Charge Transport down to 10 K

The integration of functional proteins into solid-state electronic devices remains a central challenge in molecular bioelectronics due to the fragile nature of protein structures and their complex charge-transport behaviour. Here, we present a robust crosswire evaporated top-contact device based on bacteriorhodopsin (bR) single bilayers (SBL), configured as Au/Cys/bR(SBL)/eC/Au (simplified as Au/bR/eC). The evaporated carbon (eC) top electrode forms a conformal, non-invasive contact that suppresses filament formation and ensures electrical integrity across the cross-wire intersecting area (about 200 micron^2). Structural and spectroscopic analyses confirm that the solid-state bR films maintain the native absorption spectrum and have functional photocycle activity after electrode deposition, implying that their native conformation is not significantly affected. Remarkably, electron transport (ETp) through the 9 nm bR-SBL junctions is temperature-independent within 300 K - 10 K, excluding thermally activated hopping, while the length is incompatible with coherent tunneling. Under green illumination, the junctions exhibit a reversible, photo-induced current enhancement (Jgreen/Jdark = 2), ascribed to light-driven conformational changes rather than direct photoexcitation. The Au/bR/eC architecture thus establishes a thermally non-activated, conformationally mediated transport mechanism via a stable, cryo-compatible solid-state protein junction. This work provides a scalable platform for integrating light-responsive biomolecules into future bio-optoelectronic and neuromorphic devices.

physics.bio-ph↗

arXiv2022

Spectroscopy and structural investigation of iron phosphorus trisulfide -- FePS$_3$

Lamellar structures of transition metal phosphorus trisulfides possess strong intralayer bonding, albeit adjacent layers are held by weak van der Waals interactions. Those compounds received enormous interest due to their unique combination of optical and long-range magnetic properties. Among them, iron phosphorus trisulfide (FePS$_3$) gathered special attention for being a semiconductor with an absorption edge in the near-infrared, as well as showing an Ising-like anti-ferromagnetism. We report a successful growth of centimeter size bulk FePS$_3$ crystals with a chemical yield above 70%, whose crystallographic structure and composition were carefully identified by advanced electron microscopy methodologies, including atomic resolution elemental mapping, along with photoelectron spectroscopy. The knowledge on the optical activity of FePS$_3$ is extended utilizing temperature-dependent absorption and photoacoustic spectroscopies, while measurements were corroborated with density-functional theory calculations. Temperature-dependent experiments showed a small and monotonic band-edge energy shift down to 115 K and exposed the interconnected importance of electron-phonon coupling. Most of all, the correlation between the optical behavior and the magnetic phase transition is revealed, which shows the practical utilization of temperature-dependent optical absorption to investigate magnetic interactions.

cond-mat.mtrl-sci↗

arXiv2015

Cesium Enhances Long-Term Stability of Lead Bromide Perovskite-Based Solar Cells

Direct comparison between perovskite-structured hybrid organic-inorganic - methyl ammonium lead bromide (MAPbBr3) and all-inorganic cesium lead bromide (CsPbBr3), allows identifying possible fundamental differences in their structural, thermal and electronic characteristics. Both materials possess a similar direct optical band-gap, but CsPbBr3 demonstrates a higher thermal stability than MAPbBr3. In order to compare device properties we fabricated solar cells, with similarly synthesized MAPbBr3 or CsPbBr3, over mesoporous titania scaffolds. Both cell types demonstrated comparable photovoltaic performances under AM1.5 illumination, reaching power conversion efficiencies of ~6 % with a poly-aryl amine-based derivative as hole transport material. Further analysis shows that Cs-based devices are as efficient as, and more stable than methyl ammonium-based ones, after aging (storing the cells for 2 weeks in a dry (relative humidity 15-20%) air atmosphere in the dark) for 2 weeks, under constant illumination (at maximum power), and under electron beam irradiation.

cond-mat.mtrl-sci↗