arXiv subjects

P. M. Marychev

Publications and source records attributed to P. M. Marychev.

9 recordsLinked to original sources

arXiv2023

The Type-II/Type-I Crossover in Dirty Ferromagnetic Superconductors

In this work we investigate the intertype (IT) domain in strongly disordered ferromagnetic superconductors with a Curie temperature lower than the superconducting critical temperature. In such unique materials, the coexistence of superconductivity and ferromagnetism allows for the exploration of both unconventional superconductivity and interplay between magnetism and superconductivity. The study utilizes an extended Ginzburg-Landau model for the dirty limit to calculate the boundaries of the IT domain which is characterized by a complex vortex-vortex interaction and exotic vortex configurations. The analysis reveals that the IT domain in dirty ferromagnetic superconductors is not qualitatively different from the clean case and remains similarly large, suggesting that disorder does not hinder the exploration of the rich variety of IT superconductivity in ferromagnetic superconductors. This work expands understanding of the interplay between superconductivity and magnetism in complex materials and could guide future experimental studies.

cond-mat.supr-con↗

arXiv2023

Intertype superconductivity evoked by the interplay of disorder and multiple bands

Nonmagnetic impurity scattering is known to shift up the Ginzburg-Landau parameter $κ$ of a superconductor. In this case, when the system is initially in type I, it can change its magnetic response, crossing the intertype domain with $κ\sim 1$ between the two standard superconductivity types and arriving at type II. In the present work we demonstrate that the impact of disorder can be much more profound in the presence of the multiband structure of the charge carrier states. In particular, when the band diffusivities differ from each other, the intertype domain tends to expand significantly, including points with $κ\gg 1$ that belong to deep type-II in conventional single-band superconductors. Our finding sheds light on the nontrivial disorder effect and significantly complements earlier results on the enlargement of the intertype domain in clean multiband superconductors.

cond-mat.supr-con↗

arXiv2022

Peak effect in a superconductor/normal metal strip being in vortex-free state

We theoretically predict that the critical current $I_c$ and magnetization $M$ of hybrid superconductor/normal-metal (SN) strip may have nonmonotonous dependence on perpendicular magnetic field - so called peak effect. In contrast to familiar peak effect, which is connected either with vortex entry to the superconductor or with peculiarities of vortex pinning, the found phenomenon exists at low fields, in the vortex-free (Meissner) phase. We argue that the effect appears at specific parameters of studied hybrid structure when its in-plane current-supervelocity relation has two maxima. We expect that the same peak effect may exist in two-band superconductors (like MgB$_2$) where similar current-supervelocity dependence was predicted at low temperatures.

cond-mat.supr-con↗

arXiv2020

Magnetic field induced global paramagnetic response in Fulde-Ferrell superconducting strip

We theoretically study magnetic response of a superconductor/ferromagnet/normal-metal (SFN) strip in an in-plane Fulde--Ferrell (FF) state. We show that unlike to ordinary superconducting strip the FF strip can be switched from diamagnetic to paramagnetic and then back to diamagnetic state by {\it increasing} the perpendicular magnetic field. Being in paramagnetic state FF strip exhibits magnetic field driven second order phase transition from FF state to the ordinary state without spatial modulation along the strip. We argue that the global paramagnetic response is connected with peculiar dependence of sheet superconducting current density on supervelocity in FF state and it exists in nonlinear regime.

cond-mat.supr-con↗

arXiv2020

Josephson junction based on highly disordered superconductor/low-resistive normal metal bilayer

We calculate current-phase relation (CPR) of a SN-S-SN Josephson junction based on a variable thickness SN bilayer composed of highly disordered superconductor (S) and low-resistive normal metal (N) with proximity induced superconductivity. In case when the thickness of S,N layers and length of S constriction is about of superconducting coherence length the CPR is single-valued, could be close to sinusoidal one and the product $I_cR_n$ can reach $Δ(0)/2|e|$ ($I_c$ is the critical current of the junction, $R_n$ is its normal-state resistance, $Δ(0)$ is the superconductor gap of single S layer at zero temperature). We argue that the normal layer should provide good heat removal from S constriction and there is range of parameters when current-voltage characteristic is not hysteretic and $I_cR_n$ is relatively large.

cond-mat.supr-con↗

arXiv2018

Tuning in-plane FFLO state in superconductor-ferromagnet-normal metal hybrid structure by magnetic field or current

Temperature induced transition of thin superconductor-ferromagnet-normal (S/F/N) metal hybrid structure to in-plane Fulde-Ferrel-Larkin-Ovchinnikov (FFLO) state is accompanied by vanishing of effective inverse magnetic field penetration depth $Λ^{-1}$ (Phys. Rev. Lett. 121, 077002 (2018)). Here we show that $Λ^{-1}$ goes to zero only in limit of zero magnetic field $H \to 0$ and at any finite parallel $H$ or in-plane current $I$ it is finite and positive in FFLO state which implies diamagnetic response. We demonstrate that $Λ^{-1}$ has a nonmonotonic dependence on $H$ and $I$ not only in the parameter range corresponding to the FFLO phase domain but also in its vicinity. We find that for S/F/N/F/S structures with certain thicknesses of F layers there is temperature, current and magnetic field driven transition to and out of FFLO phase with a simultaneous jump of $Λ^{-1}$.

cond-mat.supr-con↗

arXiv2017

Soliton induced critical current oscillations in two-band superconducting bridges

Using time-dependent Ginzburg-Landau theory we find oscillations of critical current density $j_c$ as a function of the length $L$ of the bridge formed from two-band superconductor. We explain this effect by appearance of the phase solitons in the bridge at $j<j_c$, those number changes with change of $L$. In case of sufficiently strong interband coupling oscillations of $j_c$ disappear.

cond-mat.supr-con↗

arXiv2017

Threshold fluctuations in a superconducting current-carrying bridge

We calculate the energy of threshold fluctuation $δF_{thr}$ which triggers the transition of superconducting current-carrying bridge to resistive state. We show that the dependence $δF_{thr}(I)\propto I_{dep}\hbar(1-I/I_{dep})^{5/4}/e$, found by Langer and Ambegaokar for a long bridge with length $L \gg ξ$, holds far below the critical temperature both in dirty and clean limits (here $I_{dep}$ is the depairing current of the bridge and $ξ$ is a coherence length). We also find that even 'weak' local defect (leading to the small suppression of the critical current of the bridge $I_c \lesssim I_{dep}$) provides $δF_{thr}\propto I_c\hbar(1-I/I_c)^{3/2}/e$, typical for a short bridge with $L \ll ξ$ or a Josephson junction.

cond-mat.supr-con↗

arXiv2016

Threshold Perturbations in Current-Carrying Superconducting Bridges with a Finite Length near the Critical Temperature

Near the critical temperature of a superconducting transition, the energy of the threshold perturbation $δF_{thr}$ that transfers a superconducting bridge to a resistive state at a current below the critical current $I_c$ has been determined. It has been shown that $δF_{thr}$ increases with a decrease in the length of a bridge for short bridges with lengths $L<ξ$ (where $ξ$ is the coherence length) and is saturated for long bridges with $L\gg ξ$. At certain geometrical parameters of banks and bridge, the function $δF_{thr}(L)$ at the current $I\to 0$ has a minimum at $L\sim 2-3 ξ$. These results indicate that the effect of fluctuations on Josephson junctions made in the form of short superconducting bridges is reduced and that the effect of fluctuations on bridges with lengths $\sim 2-3 ξ$ is enhanced.

cond-mat.supr-con↗