Dynamics and heat diffusion of Abrikosov's vortex-antivortex pairs during an annihilation process

A Phase Transition in U(1) Configuration Space: Oscillons as Remnants of Vortex-Antivortex Annihilation

We show that the low-momentum scattering of vortex-antivortex pairs can lead to very long-lived oscillon states in 2d Abelian Higgs models. The emergence of oscillons is controlled by the ratio of scalar and vector field masses, $β=(m_s/m_v)^2$ and can be described as a phase transition in field configuration space with critical value $β_c\simeq 0.13(6)\pm 2 $: only models with $β<β_c$ lead to oscillon-like remnants. The critical behavior of the system obeys a power law $O(β)\sim |β-β_c|^o$, where $O$ is an order parameter indicating the presence of oscillons and $o = 0.2(2)\pm 2 $ is the crit…

Dynamics of driven vortex-antivortex matter in superconducting films with a magnetic dipole array

We investigate theoretically vortex-antivortex (v-av) matter moving in thin superconducting films with a regular array of in-plane magnetic dipoles. Our model considers v-av pair creation induced by the local current density generated by the magnetic texture and the transport current and simulates the dynamics of vortices and antivortices by numerical integration of the Langevin equation of motion. Calculations of the transport properties at zero applied field show a strong dependence of the v-av dynamics on the current intensity and direction. The dynamics of the v-av matter is characterized …

Direct Evidence of Spontaneous Abrikosov Vortex State in Ferromagnetic Superconductor EuFe$_2$(As$_{1-x}$P$_x$)$_2$ with $x=0.21$

Using low-temperature Magnetic Force Microscopy (MFM) we provide direct experimental evidence for spontaneous vortex phase (SVP) formation in EuFe$_2$(As$_{0.79}$P$_{0.21}$)$_2$ single crystal with the superconducting $T^{\rm 0}_{\rm SC}=23.6$~K and ferromagnetic $T_{\rm FM}\sim17.7$~K transition temperatures. Spontaneous vortex-antivortex (V-AV) pairs are imaged in the vicinity of $T_{\rm FM}$. Also, upon cooling cycle near $T_{\rm FM}$ we observe the first-order transition from the short period domain structure, which appears in the Meissner state, into the long period domain structure with …

Second generation of vortex-antivortex states in mesoscopic superconductors: stabilization by artificial pinning

Antagonistic symmetries of superconducting polygons and their induced multi-vortex states in a homogeneous magnetic field may lead to appearance of antivortices in the vicinity of the superconducting/normal state boundary (where mesoscopic confinement is particularly strong). Resulting vortex-antivortex (V-Av) molecules match the sample symmetry, but are extremely sensitive to defects and fluctuations and remain undetected experimentally. Here we show that V-Av states can re-appear deep in the superconducting state due to an array of perforations in a polygonal setting, surrounding a central h…

具有本征二极管效应的超导结构中的涡旋结构与涡旋间相互作用

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

本研究通过GL理论与数值模拟，揭示本征超导二极管效应导致涡旋手性畸变、非中心相互作用力及力矩，并破缺涡旋-反涡旋对称性，为设计非互易超导器件提供指导。

Topological transitions in superconductor nanomembranes in a magnetic field with submicron inhomogeneity under a strong transport current

Under a strong transport current, the induced voltage in superconductor nanomembranes in a magnetic field with submicron inhomogeneity shows a pulse on a certain interval of the magnetic field. It is a manifestation of a wide phase-slip domain. The topological transition accompanying the phase-slip effect consists in the occurrence of two new loops of weak superconducting currents connecting two regions of superconducting screening currents, which are disconnected in case of vortex-chain dynamics. In the middle of the phase-slip domain, rapid dynamics of the superconducting order parameter con…

Generating superconducting vortices via spin-orbit coupling

Spin-orbit coupling (SOC) is known to play an important role in superconductor/ferromagnet heterostructures. Here we demonstrate that SOC results in the spontaneous generation of vortices in an \textit{s}-wave superconductor placed below a ferromagnetic metal with intrinsic or interfacial SOC. By using the generalized London and Ginzburg-Landau theories, we calculate the supercurrent amplitude in various types of S/F heterostructures at and below the superconducting critical temperature. In particular, we show that even in the limit of weak SOC, vortex-antivortex pairs are stabilized and that …

Ultra-fast Kinematic Vortices in Mesoscopic Superconductors: The Effect of the Self-Field

Within the framework of the generalized time-dependent Ginzburg-Landau equations, we studied the influence of the magnetic self-field induced by the currents inside a superconducting sample driven by an applied transport current. The numerical simulations of the resistive state of the system show that neither material inhomogeneity nor a normal contact smaller than the sample width are required to produce an inhomogeneous current distribution inside the sample, which leads to the emergence of a kinematic vortex-antivortex pair (vortex street) solution. Further, we discuss the behaviors of the …

超导单光子探测器中光子检测机制的理论分析

Theoretical analysis of photon detection mechanism in superconducting single-photon detectors

该研究通过理论分析揭示了超导单光子探测器中光子检测机制，探讨了热点模型与涡旋-反涡旋对的动力学影响，并提供了设备设计的指导。

Dynamics of vortex penetration, jumpwise instabilities and nonlinear surface resistance of type-II superconductors in strong rf fields

We consider nonlinear dynamics of a single vortex in a superconductor in a strong rf magnetic field $B_0\sinωt$. Using the London theory, we calculate the dissipated power $Q(B_0,ω)$, and the transient time scales of vortex motion for the linear Bardeen-Stephen viscous drag force, which results in unphysically high vortex velocities during vortex penetration through the oscillating surface barrier. It is shown that penetration of a single vortex through the ac surface barrier always involves penetration of an antivortex and the subsequent annihilation of the vortex antivortex pairs. Using the …

Flux noise in high-temperature superconductors

Spontaneously created vortex-antivortex pairs are the predominant source of flux noise in high-temperature superconductors. In principle, flux noise measurements allow to check theoretical predictions for both the distribution of vortex-pair sizes and for the vortex diffusivity. In this paper the flux-noise power spectrum is calculated for the highly anisotropic high-temperature superconductor Bi-2212, both for bulk crystals and for ultra-thin films. The spectrum is basically given by the Fourier transform of the temporal magnetic-field correlation function. We start from a Berezinskii-Kosterl…

铁磁超导体中的磁控涡旋动力学

Magnetically-controlled Vortex Dynamics in a Ferromagnetic Superconductor

研究铁磁超导体EuFe$_2$(As$_{1-x}$P$_x$)$_2$中底层磁结构对外加磁场下超导涡旋动力学的控制机制，揭示了涡旋极化子的形成及涡旋-反涡旋湮灭势垒对临界电流的影响，为高电流导体中磁增强涡旋钉扎提供了新途径。