arXiv subjects

A. I. Buzdin

Publications and source records attributed to A. I. Buzdin.

At least 19 recordsLinked to original sources

arXiv2026

Perspectives on Magnetic/Superconductor Hybrid Systems: Long-range Electromagnetic Phenomena Induced by Proximity Effect and Interfacial Spin-orbit Coupling

In this Perspective we review recent achievements in physics and applications of hybrid superconductor-ferromagnet structures. In particular, we focus on the manifestations of the electromagnetic phenomena in these systems originating from the response of the induced superconducting correlations modified by the exchange field and additional effects coming from the interface Rashba-type spin-orbit coupling. The review includes the long-range electromagnetic proximity effect and related modification of magnetic textures, spontaneous currents, properties of vortex matter and its interaction with magnetic ordering, spin-galvanic, photogalvanic and nonreciprocal transport phenomena in exemplary hybrid systems. We also present our views on the future development of this field including both the theoretical challenges and promising opportunities for fundamental experiments.

cond-mat.supr-con↗

arXiv2025

Photogalvanic and photon drag phenomena in superconductors and hybrid superconducting systems

In this paper we review the recent progress in theoretical understanding of the peculiarities of photogalvanic phenomena, photon drag and inverse Faraday effects in superconductors and hybrid superconducting structures. Our study is based on the time-dependent Ginzburg-Landau (TDGL) theory with a complex relaxation constant which provides the simplest description of the mechanisms of the second-order nonlinear effects in the electrodynamic response and related mechanisms of generation of dc photocurrents, magnetic moment and switching between different current states under the influence of electromagnetic radiation of various polarization.

cond-mat.supr-con↗

arXiv2025

Vortex structure and intervortex interaction in superconducting structures with intrinsic diode effect

We demonstrate that the intrinsic superconducting diode effect can affect the structure, interactions and dynamics of Abrikosov vortices in non-centrosymmetric superconductor/ferromagnet hybrid structures. The Ginzburg-Landau (GL) theory accounting for the spin-orbit and exchange-field effects predicts a chiral distortion of the superfluid velocity, non-central interaction forces and resulting torque in a vortex-antivortex pair, and anisotropy of the Bean-Livingston barrier. These closed-form results are fully confirmed by time-dependent GL numerical simulations carried out with a fourth-order least-squares finite-difference solver, which captures equilibrium single vortex configuration in realistic mesoscopic geometries. The analysis shows that the cubic gradient term shifts vortex cores by an amount proportional to the in-plane exchange field and simultaneously generates a lateral torque that can rotate entire vortex ensembles, showing how spin-orbit coupling and the exchange field enable breakdown of the vortex-antivortex symmetry in a finite-size sample. By combining transparent analytics with quantitative numerics, the work provides the hallmarks of vortex physics in superconducting structures with an intrinsic diode effect and supplies concrete guidelines for designing non-reciprocal superconducting circuits, fluxonic logic elements, and kinetic-inductance devices.

cond-mat.supr-con↗

arXiv2024

Inverse spin galvanic effect in proximitized superconductor/paramagnet systems

We show that the interplay between spin-orbit coupling (SOC) and the paramagnetic response of itinerant electrons in proximitized superconductor/paramagnet systems gives rise to the inverse spin galvanic effect, i.e. generation of magnetic moment under the influence of the charge current. Depending on the sign of the SOC constant and the system temperature, the corresponding contribution to the magnetic response of the superconductor can be either diamagnetic or paramagnetic. We discuss the relevance between the discovered phenomena and the recent experiments on Pt/Nb heterostructures as well as the puzzling sign change of the magnetic response observed in clean Ag coated Nb cylinders.

cond-mat.supr-con↗

arXiv2024

Photogalvanic phenomena in superconductors supporting intrinsic diode effect

In this work we suggest a phenomenological theory of photogalvanic phenomena in superconducting materials and structures revealing the diode effect. Starting from a generalized London model including the quadratic nonlinearity in the relation between the supercurrent and superfluid velocity we show that the electromagnetic wave incident on the superconductor can generate a nontrivial superconducting phase difference between the ends of the sample. Being enclosed in a superconducting loop such phase battery should generate a dc supercurrent circulating in the loop. Increasing the electromagnetic wave intensity one can provoke the switching between the loop states with different vorticities.

cond-mat.supr-con↗

arXiv2024

Interfacial spin-orbit coupling driven enhancement of superconductivity by parallel magnetic field

It is commonly believed that time reversal symmetry breaking perturbations such as magnetic field or scattering on magnetic impurities destruct superconductivity and suppress the critical temperature of the superconducting phase transition. However, in the recent experimental studies significant enhancement of superconducting critical temperature by parallel magnetic field was found for several thin superconducting systems [H.J. Gardner, et al., Nature Physics {\bf 7}, 895 (2011); T. Asaba, et al., Scientific Reports {\bf 8}, 1 (2018) ]. Here we present a possible explanation of the observed phenomenon showing that combination of interfacial spin-orbit interaction and external magnetic field can cause the increase of the superconducting critical temperature of thin superconducting film in wide range of magnetic fields. We use the Ginzburg-Landau formalism taking into account Lifshitz invariant originated from Rashba spin-orbit interaction, which is also responsible for the superconducting diode effect. We also calculate the modification of the Little-Parks oscillations of the critical temperature of hollow superconducting cylinder at the presence of Rashba interfacial spin-orbit interaction.

cond-mat.supr-con↗

arXiv2024

ac Hall Effect and Photon Drag of Superconducting Condensate

We suggest a theoretical description of the photogalvanic phenomena arising in superconducting condensates in the field of electromagnetic wave. The ac Hall effect and photon drag are shown to originate from the second-order nonlinear response of superconducting carriers caused by the suppression of their concentration due to the combined influence of the electron - hole asymmetry and charge imbalance generated by the incident electromagnetic wave. Starting from the time-dependent Ginzburg-Landau theory with the complex relaxation constant we develop a phenomenological description of these phenomena and investigate the resulting behavior of the dc supercurrent and second harmonic induced by microwave radiation incident on a superconductor surface.

cond-mat.supr-con↗

arXiv2023

Non-reciprocal electron transport in finite-size superconductor/ferromagnet bilayers with strong spin-orbit coupling

We show that spin-orbit coupling at the interface between a superconducting film of the finite lateral size and the underlying ferromagnetic insulator with in-plane exchange field gives rise to a series of non-reciprocal effects provided the superconducting pairing is enhanced near the boundaries of the superconductor due to, e.g., variation of the film thickness or of the interlayer electron transparency. Specifically, the critical temperature and the critical depairing current are shown to depend on the relative orientation between the exchange field in the ferromagnet and the superconducting film boundaries. The discovered anisotropy of the superconducting properties is promising for the design of diode-type elements in superconducting spintronics.

cond-mat.supr-con↗

arXiv2023

Adiabatic phase pumping in S/F/S hybrids with non-coplanar magnetization

We study the distinctive features of the phase pumping effect in Josephson transport through a three-layered ferromagnet F$_1$/F/F$_2$ with non-coplanar magnetization. Using Gor'kov and Bogoliubov-de Gennes formalisms we go beyond the quasiclassical approximation and analyze the dependence of the spontaneous Josephson phase $ψ$ on the exchange field $h$ in the F layer and details of magnetization profile. The pumping of the Josephson phase can be generated by the mutual rotation of magnetizations in F$_1$ and F$_2$ layers resulting in the nontrivial phase gain at the rotation period (Berry phase). The increase in $h$ is shown to cause changes in the topology of the phase evolution: the gain of the Josephson phase at the pumping period switches from $0$ to $2π$. We study the scenario of these switchings originating from the interplay between several competing local minima of the free energy of the junction versus the superconducting phase difference. Our analysis provides the basis for the search of experimental setup realizing the phase pumping phenomenon.

cond-mat.supr-con↗

arXiv2023

Collisionless dynamics of superconducting gap excited by spin-splitting field

We study the coherent dynamic interaction of a time-dependent spin-splitting field with the homogeneous superconducting order parameter $Δ(t)$ mediated by spin-orbit coupling using the time-dependent Bogoliubov-de Gennes theory. In the first part of the work we show that linear response of the superconductor is strongly affected by the Zeeman field and spin-flip processes, giving rise to multiple resonant frequencies of the superconducting Higgs modes. These modes can be excited either by a quench, or by an additional non-stationary component of the spin-splitting field, which couples linearly to the Higgs modes. In the second part, we analyze the nonadiabatic dynamics of quasiparticle states arising from the intersection of spectral branches from different spin subbands, which can be provoked by a linearly growing Zeeman field. We provide insights into the dependence of the order parameter $Δ(t)$ on this field and interference effects caused by tunneling of states at the avoided crossing points. We also show that since the nonadiabatic tunneling is related to spin-flip processes, the quasiparticle gas experiences a dynamic magnetization that contributes to its spin susceptibility.

cond-mat.supr-con↗

arXiv2023

Cherenkov radiation of spin waves by ultra-fast moving magnetic flux quanta

Despite theoretical predictions for a Cherenkov-type radiation of spin waves (magnons) by various propagating magnetic perturbations, fast-enough moving magnetic field stimuli have not been available so far. Here, we experimentally realize the Cherenkov radiation of spin waves in a Co-Fe magnonic conduit by fast-moving (>1 km/s) magnetic flux quanta (Abrikosov vortices) in an adjacent Nb-C superconducting strip. The radiation is evidenced by the microwave detection of spin waves propagating a distance of 2 micrometers from the superconductor and it is accompanied by a magnon Shapiro step in its current-voltage curve. The spin-wave excitation is unidirectional and monochromatic, with sub-40 nm wavelengths determined by the period of the vortex lattice. The phase-locking of the vortex lattice with the excited spin wave limits the vortex velocity and reduces the dissipation in the superconductor.

cond-mat.other↗

arXiv2023

All-optical generation of Abrikosov vortices by the Inverse Faraday Effect

Within the framework of the time-dependent Ginzburg-Landau theory we show that circularly polarized THz or far-infrared radiation induces a dc supercurrent that influences the dynamics of vortex-antivortex pair formation in a mesoscopic superconductor undergoing rapid thermal quenching. The Lorentz force arising from the supercurrents promotes vortex-antivortex separation and allows survival of the vortex polarity defined by the helicity of light. Based on this idea, we propose a two-stage irradiation scheme that provides a powerful method for controlled all-optical generation of Abrikosov vortices.

cond-mat.supr-con↗

arXiv2022

Giant electromagnetic proximity effect in superconductor/ferromagnet superlattices

We show that in superlattices with alternating superconducting (S) and ferromagnetic (F) layers the spontaneous magnetic field induced in the superconducting layers due to the electromagnetic proximity effect becomes dramatically enhanced compared to the previously studied S/F bilayers. The effect reveals itself for the in-plane orientation of the magnetic moments both for ferromagnetic and anti-ferromagnetic ordering of the moments in the F layers. In the finite size samples the magnetic field decays from the sample surface towards the bulk of the structure, and the decay length strongly depends on the relative orientation of the sample surface, the layers planes and magnetic moments in the F layers. The obtained results provide additional insights into experimental data on the neutron scattering in Nb/Gd superlattices.

cond-mat.supr-con↗

arXiv2021

Collective magnetic and plasma excitations in Josephson $ψ$ junctions

We show that Josephson $ψ$ junctions with the half-metallic (HM) weak link coupled to the superconducting (S) electrodes through the ferromagnetic (F) layers host collective excitations of magnetic moment and the Josephson phase. This results in the shift of the ferromagnetic resonance frequency, anomalies in the current-voltage characteristics and the appearance of additional magnetic anisotropy in the F layers. In contrast to the previously studied S/F/S junctions, the coupling between magnetic and plasma modes emerges even in the long-wavelength limit. Such coupling is shown to enable the controllable magnetization reversal in the F layer governed by the d.c. current pulse which provides the effective mechanism for magnetic moment manipulation in the devices of superconducting spintronics.

cond-mat.supr-con↗

arXiv2021

Giant demagnetization effects induced by superconducting films

We show that a ferromagnetic (F) slab with the in-plane magnetization sandwiched between two superconducting (S) films experiences strong demagnetization effect due to the Meissner screening of the stray magnetic field by the superconductors. In the extreme case the transition of the S films from normal to the superconducting state can switch the demagnetization factor from 0 to 1 which is in a sharp contrast with the S/F bilayers where such transition affects the magnetic field inside the F film only slightly. The giant demagnetization effect is shown to be qualitatively robust against the decreasing of the superconducting film thickness and may provide a hint towards the explanation of the anomalously large ferromagnetic resonance frequency shift recently observed for the S/F/S structures [I. A. Golovchanskiy, N. N. Abramov, V. S. Stolyarov, V. I. Chichkov, M. Silaev, I. V. Shchetinin, A. A. Golubov, V. V. Ryazanov, A. V. Ustinov, and M. Yu. Kuprianov, Phys. Rev. Appl. 14, 024086 (2020)].

cond-mat.supr-con↗

arXiv2021

Inverse Faraday Effect for Superconducting Condensates

The Cooper pairs in superconducting condensates are shown to acquire a temperature-dependent dc magnetic moment under the effect of the circularly polarized electromagnetic radiation. The mechanisms of this inverse Faraday effect are investigated within the simplest version of the phenomenological dynamic theory for superfluids, namely, the time-dependent Ginzburg-Landau (GL) model. The light-induced magnetic moment is shown to be strongly affected by the nondissipative oscillatory contribution to the superconducting order parameter dynamics which appears due to the nonzero imaginary part of the GL relaxation time. The relevance of the latter quantity to the Hall effect in superconducting state allows to establish the connection between the direct and inverse Faraday phenomena.

cond-mat.supr-con↗

arXiv2021

Phase transitions in superconductor/ferromagnet bilayer driven by spontaneous supercurrents

We investigate superconducting phase transition in superconductor(S)/ferromagnet(F) bilayer with Rasba spin-orbit interaction at S/F interface. This spin-orbit coupling produces spontaneous supercurrents flowing inside the atomic-thickness region near the interface, which are compensated by the screening Meissner currents [S. Mironov and A. Buzdin, Phys. Rev. Lett \textbf{118}, 077001 (2017)]. In the case of thin superconducting film the emergence of the spontaneous surface currents causes the increase of the superconducting critical temperature and we calculate the actual value of the critical temperature shift. We also show that in the case of type-I superconducting film this phase transition can be of the first order. In the external magnetic field the critical temperature depends on the relative orientation of the external magnetic field and the exchange field in the ferromagnet. Also we predict the in-plane anisotropy of the critical current which may open an alternative way for the experimental observation of the spontaneous supercurrents generated by the SOC.

cond-mat.supr-con↗

arXiv2021

Penetration depth of Cooper pairs in the IrMn antiferromagnet

Suppression of superconductivity due to the proximity effect between a superconductor and a ferromagnet can be partially alleviated when a Cooper pair simultaneously samples different directions of the short-range exchange field. The superconductor's critical temperature, TC, is therefore expected to partially recover when the ferromagnet is in a multi-domain state, as opposed to a single-domain state. Here, we discuss series of experiments performed with ferromagnet(Pt/Co)/spacer(IrMn and Pt)/superconductor(NbN) heterostructures. By tuning the various parameters in play, e.g., superconducting coherence length-to-thicknesses ratio, and domain sizes, we obtained up to 10 percent recovery of the superconducting critical temperature ΔTC/TC. This large-scale recovery made novel investigations possible. In particular, from the spacer thickness-dependence of ΔTC/TC, it was possible to deduce the characteristic length for Cooper pair penetration in an IrMn antiferromagnet. This information is crucial for electronic transport, and up to now has been difficult to access experimentally for antiferromagnets.

cond-mat.mtrl-sci↗