Abstract Investigation of vortex pinning and its relaxation is great importance for both basic physics technological applications in the field superconductivity. We report a improvement superconducting properties recently discovered 112-type superconductors (Ca, La)FeAs 2 through Co co-doping. High critical current density J s (5 K) > * 10 6 A/cm obtained pronounced second peak effect observed magnetization hysteresis loops. Both dynamic static studies result comparable sizable rates S or...

Strain engineering enables precise, energy-efficient control of nanoscale magnetism. However, unlike well-studied strain-dislocation interactions in mechanical deformation, the spatial evolution strain-induced spin rearrangement remains poorly understood. Using Lorentz transmission electron microscopy, we manipulate and observe helical domain reorientation under quantitatively applied uniaxial tensile stress. Our findings reveal striking similarity to plastic deformation metals, where...

We analyzed pattern formation and identified various morphologies in a system of particles interacting through non-monotonic potential with competing range interaction characterized by repulsive core (r < rc) an attractive tail > rc), using molecular-dynamics simulations. Depending on parameters, the models inter-particle physical systems ranging from atoms, molecules colloids to vortices low κ type-II superconductors recently discovered 'type-1.5' superconductors. constructed 'morphology...

We analyze theoretically and experimentally vortex configurations in mesoscopic superconducting squares. Our theoretical approach is based on the analytical solution of London equation using Green's-function method. The potential-energy landscape found for each configuration then used Langevin-type molecular-dynamics simulations to obtain stable configurations. Metastable states transitions between them ground state are analyzed. present our results first direct visualization patterns...

Non-equilibrium self-organized patterns formed by particles interacting through competing range interaction are driven over a substrate an external force. We show that, with increasing driving force, the pre-existed static evolve into dynamic either via disordered phase or depinned patterns, formation of non-equilibrium stripes. Strikingly, stripes in direction force transverse direction, depending on pinning strength. The revealed dynamical summarized diagram.

High-quality single crystal Ca0.8La0.2Fe0.98Co0.02As2 has been successfully synthesized using a self-flux method. The magnetization measurement reveals second peak effect and high critical current density exceeding 2 × 106 A cm−2 at 5 K (self-field). upper field anisotropy was systematically studied by measuring the electrical resistivity under various magnetic fields angles. angle-dependent magnetoresistance, choosing an appropriate parameter within framework of anisotropic Ginzburg–Landau...

Real-space topological magnetic structures such as skyrmions and merons are promising candidates for information storage transport. However, the microscopic mechanisms that control their formation evolution still unclear. Here, using in situ Lorentz transmission electron microscopy, we demonstrate skyrmion crystals (SkXs) can nucleate, grow, evolve from conical phase same ways real nanocrystals form vapors or solutions. More intriguingly, individual also "reproduce" by division a...

Triangular-shaped mesoscopic superconductors are consistent with the symmetry of Abrikosov vortex lattice resulting in a high stability patterns for commensurate vorticities. However, non-commensurate vorticities, configurations triangles not compatible sample shape. Here we present first direct observation μm-sized niobium using Bitter decoration technique, and analyze states by analytically solving London equations performing molecular-dynamics simulations. We found that filling rules...

Controlling the interlayer coupling in two-dimensional (2D) materials generates novel electronic and topological phases. Its effective implementation is commonly done with a transverse electric field. However, phases generated by high displacement fields are elusive this standard approach. Here, we introduce an exceptionally large field structural modification of model system: AB-stacked bilayer graphene (BLG) on SiC(0001) surface. We show that upon intercalation gadolinium, states top...

We study vortex configurations in mesoscopic superconducting squares. Our theoretical approach is based on the analytical solution of London equation using Green's function method. The potential energy landscape found then used Langevin-type molecular-dynamics simulations to obtain stable configurations. show that filling rules for vortices squares with increasing applied magnetic field can be formulated, although a different manner than disks, terms formation 'shells'. discuss metastable...

We study theoretically the simultaneous effect of regular and random pinning potentials on vortex lattice structure at filling factor 1. This is determined by a competition between square symmetry array, intervortex interaction favoring triangular symmetry, randomness trying to depin vortices from their positions. Both analytical molecular-dynamics approaches are used. construct phase diagram system in plane strengths determine typical defects appearing due disorder. find that total...

We investigate the effects related to vortex-core deformations when vortices approach each other. As a result of these deformations, vortex-vortex interaction effectively acquires an attractive component leading variety vortex patterns typical for systems with nonmonotonic repulsive-attractive interaction, such as stripes and labyrinths. The core are anisotropic can induce frustration in interaction. In turn, this has impact on resulting patterns, which analyzed presence additional random...

Since it can describe the rotation curves of galaxies without dark matter and give rise to accelerated expansion, conformal gravity attracts much attention recently. As a theory modified gravity, is important test with astrophysical observations. Here we constrain SNIa Hubble parameter data investigate whether suffers from an age problem APM~08279+5255. We find accommodate APM~08279+5255 at 3 $\sigma$ deviation, unlike most energy models which suffer problem.

Abstract Electrical transport of both longitudinal and transverse directions carries rich information. Mobility spectrum analysis (MSA) is capable extracting charge information from conductivity tensor, including types, concentration mobilities. Using a numerical method based on maximum entropy principle, i.e., mobility (MEMSA), for $$\beta $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>β</mml:mi> </mml:math> -type PtBi $$_2$$ <mml:msub> <mml:mrow/> <mml:mn>2</mml:mn>...

Using a combination of density functional theory (DFT) and spin-wave methods, we investigate the magnetic interactions spin excitations in semiconducting VI$_3$. Exchange parameters monolayer, bilayer, bulk forms are evaluated by mapping energies various configurations, calculated using DFT+$U$, onto Heisenberg model. The intralayer couplings remain largely unchanged three VI$_3$, while interlayer show stronger dependence on dimensionality materials. We calculate spectra within linear...

The influence of random pinning on the vortex dynamics in a periodic square potential under an external drive is investigated. Using numerical experiments and theoretical approach, we found several dynamical regimes motion that are different from ones for regular potential. Vortex transfer controlled by kinks antikinks, which either pre-exist system or appear spontaneously pairs then propagate. When antikinks collide, they annihilate. We provide clear physical interpretations observed features.

We calculate the photodetachment cross sections of H− in a gradient electric field based on traditional quantum approach. The system provides rare example that formulas for can be explicitly derived by both approach and closed-orbit theory. results are compared with those correct phase values theory essential necessary to produce accurate sections. Our remove some previous ambiguities assigning (G. C. Yang M. L. Du 2007 Phys. Rev. A 75 029904E).

The photodetachment cross section of H− in a linear harmonic oscillator potential is investigated. This system provides rare example that can be studied analytically by both quantum and semiclassical methods with some approximations. formulas the for different laser polarization directions are explicitly derived traditional approach closed-orbit theory. In approach, we calculate sections coordinate representation momentum representation, get same formulas. We compare theory formulas, find...

Transition metal (Co and Ni) co-doping effects are investigated on an underdoped Ca0.94La0.06Fe2As2 compound. It is discovered that electron doping from substituting Fe with transition (TM = Co, can trigger high- superconductivity around 35 K, which emerges abruptly before the total suppression of innate spin-density-wave/anti-ferromagnetism (SDW/AFM) state. Remarkably, critical temperature for remains constant against a wide range TM levels. And net density dependence superconducting based...

The dynamics of driven pancake vortices in layered superconductors is studied using molecular-dynamics simulations. We found that, with increasing driving force, for strong interlayer coupling, the preexisted vortex lines either directly depin or first transform to two-dimensional (2D) pinned states before they are depinned, depending on pinning strength. In a narrow region strengths, we an interesting repinning process, which results negative differential resistance. For weak individually...