arXiv subjects

Serhii Kruhlov

Publications and source records attributed to Serhii Kruhlov.

3 recordsLinked to original sources

arXiv2026

Disorder-driven transport in ZrN thin films grown by ion-beam-assisted sputtering

We investigate the structural and electronic transport properties of zirconium nitride (ZrN) thin films grown by dc ion-beam assisted sputtering (IBAS) as a function of nitrogen partial pressure, sputtering power and deposition temperature. Variation of growth conditions enables controlled tuning from disordered metallic and superconducting behavior to insulating transport. Increasing nitrogen flow drives an increase in sheet resistance, suppression of superconducting transition temperature, and non-metallic conduction. XRD shows no measurable change in long range crystallinity or order. In the insulating regime, low-temperature transport is well described by 3D Mott variable-range hopping (VRH), with the characteristic temperature $T_0$ increasing monotonically with sheet resistance over four orders of magnitude. Despite this strong correlation between $T_0$ and disorder, $T_c$ exhibits no systematic dependence on $T_0$, indicating a decoupling between localization physics and the superconducting energy scale. Magnetotransport measurements are not well described by the standard BCS model nor the dirty type-II Werthamer-Helfand-Hohenberg model. The phase boundary is instead captured by a free-exponent power law, $μ_0 H_{c2}(T) = μ_0 H_{c2}(0)[1 - (T/T_c)^{n}]$ with $n \approx 3.47$, and extrapolates to $μ_0 H_{c2}(0) \approx 6.4$ T. The films have an extracted coherence length of 7 nm. These results establish IBAS-grown ZrN as a broadly tunable platform for investigating disorder-driven transport and the crossover between metallic conduction, electronic localization, and superconductivity.

cond-mat.supr-con↗

arXiv2025

Room temperature reactive sputtering deposition of titanium nitride with high sheet kinetic inductance

Superconducting thin films with high intrinsic kinetic inductance $L_{k}$ are important for high-sensitivity detectors, enabling strong coupling in hybrid quantum systems, and enhancing nonlinearities in quantum devices. We report the room-temperature reactive sputtering of titanium nitride thin films with a critical temperature $T_{c}$ of \SI{3.8}{K} and a thickness of \SI{27}{nm}. Fabricated into resonators, these films exhibit a sheet kinetic inductance $L_{k, \square}$ of 394~$\textrm{pH}/\square$, as inferred from resonant frequency measurements. %from this film and measure quality factors of $4\times 10^{4}$; these quality factors are likely limited by the low resistivity wafer. X-ray diffraction analysis confirms the formation of stoichiometric TiN, with no residual unreacted titanium. The films also demonstrate a characteristic sheet resistivity of 475~$Ω/\square$, yielding an impedance an order of magnitude higher than conventional 50~$Ω$ resonators. This property could enhance microwave single\textendash photon coupling strength by an order of magnitude, offering transformative potential for hybrid quantum systems and quantum sensing. Furthermore, the high $L_{k}$ enables Kerr nonlinearities comparable to state\textendash of\textendash the\textendash art quantum devices. Combined with its relatively high $T_{c}$, this thin film presents a promising platform for superconducting devices, including amplifiers and qubits operating at higher temperatures.

cond-mat.supr-con↗

arXiv2023

Flux coupled tunable superconducting resonator

We present a design and implementation of frequency-tunable superconducting resonator. The resonance frequency tunability is achieved by flux-coupling a superconducting LC-loop to a current-biased feedline; the resulting screening current leads to a change of the kinetic inductance and shift in the resonance frequency. The thin film aluminum resonator consists of an interdigitated capacitor and thin line inductors forming a closed superconducting loop. The magnetic flux from the nearby current feedline induces Meissner shielding currents in the resonator loop leading to change in the kinetic part of the total inductance of the resonator. We demonstarte continuous frequency tuning within 160 MHz around the resonant frequency of 2.7 GHz. We show that: (1) frequency upconversion is achieved when kHz AC modulation signal is superimposed onto the DC bias resulting in sidebands to the resonator tone; (2) three-wave mixing is attained by parametrically pumping the nonlinear kinetic inductance using a strong RF pump signal in the feedline. The simple architecture is amenable to large array multiplexing and on-chip integration with other circuit components. The concept could be applied in flux magnetometers, upconverters, and parametric amplifiers operating above 4 Kelvin cryogenic temperatures when alternative high critical temperature material with high kinetic inductance is used.

cond-mat.supr-con↗