scholarly journals Supercurrent Induced by Chiral Coupling in Multiferroic/Superconductor Nanostructures

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 184
Author(s):  
Bjoern Niedzielski ◽  
Chenglong Jia ◽  
Jamal Berakdar
Keyword(s):  
Dynamic Properties ◽  
Spin Current ◽  
Magnetic Ordering ◽  
Proximity Effects ◽  
Superconducting Layer ◽  
Ginzburg Landau ◽  
Spin Ordering ◽  
Helical Magnet ◽  
Type Ii Superconductor ◽  
Coupling Characteristics

We study the transport and the superconducting dynamics in a layer of type II superconductor (SC) with a normal top layer that hosts a helical magnetic ordering that gives rise to spin-current-driven ferroelectric polarization. Proximity effects akin to this heterostructure result in an anisotropic supercurrent transport and modify the dynamic properties of vortices in the SC. The vortices can be acted upon and controlled by electric gating or other means that couple to the spin ordering in the top layer, which, in turn, alter the superconducting/helical magnet coupling characteristics. We demonstrate, using the time dependent Ginzburg–Landau approach, how the spin helicity of the top layer can be utilized for pinning and guiding the vortices in the superconducting layer.

scholarly journals Comparison of the superconducting rectangular critical fields with the same area at κ = 1.5

2019 ◽  
Vol 3 (2) ◽  
pp. 62
Author(s):  
Fuad Anwar ◽  
C Cari ◽  
Alqaan Maqbullah Ilmi
Keyword(s):  
Critical Field ◽  
Proximity Effects ◽  
Time Dependent ◽  
Type Ii ◽  
Critical Fields ◽  
Ginzburg Landau ◽  
Type Ii Superconductor ◽  
Tdgl Equation

<span>The Time Dependent Ginzburg-Landau (TDGL) equation can be used to study the characteristics of superconductors in the evolution of time to reach equilibrium. This study uses the <em>ѰU</em> method to numerically calculate critical field values more easily. Previous research has been carried out on size variations, kappa variations, proximity effects and so on. In this study, a comparison between squares and rectangles with the same size of area for type II superconductor , then it is found that the critical field Hc<sub>3</sub> is the same value for each of the same area.</span>

DILUTED FERROMAGNETIC SEMICONDUCTORS — ORIGIN OF MAGNETIC ORDERING AND SPIN-TRANSPORT PROPERTIES

2008 ◽  
Vol 22 (01n02) ◽  
pp. 104-105 ◽  
Author(s):  
TOMASZ DIETL
Keyword(s):  
Diluted Magnetic Semiconductors ◽  
Spin Transport ◽  
Correlation Energy ◽  
Tight Binding ◽  
Spin Current ◽  
Magnetic Ordering ◽  
Exchange Interactions ◽  
Ferromagnetic Phase ◽  
Magnetic Characteristics ◽  
Ferromagnetic Semiconductors

In the first hour of the lecture the present understanding of the origin of exchange interaction and mechanisms leading to ferromagnetic order in diluted magnetic semiconductors will be presented.1 The lecture will start by discussing energy positions of relevant open magnetic shells, including the correlation energy and excitations within the magnetic ions. The origin and magnitude of sp–d exchange interactions will then be described. This will be followed by presenting the physics of indirect exchange interactions between localized spins contrasting magnetic characteristics in the absence and in the presence of free carriers. The Zener and RKKY models of ferromagnetism will be introduced and the role of confinement, dimensionality, and spin-orbit interaction in determining properties of the ferromagnetic phase will be outlined. The second lecture will be devoted to theory of spin transport in layered structures of diluted ferromagnetic semiconductors, emphasizing the issues important for perspective spintronics devices. A recently developed theory,2 which combines a multi-orbital empirical tight-binding approach with a Landauer–Büttiker formalism will be presented. In contrast to the standard kp method, this theory describes properly the interfaces and inversion symmetry breaking as well as the band dispersion in the entire Brillouin zone, so that the essential for the spin-dependent transport Rashba and Dresselhaus terms as well as the tunneling via k points away from the zone center are taken into account. The applicability of this model for the description of tunneling magnetoresistance (TMR), resonant tunneling spectra, spin-current polarization in Esaki-Zener diodes, and domain-wall resistance will be presented. Note from Publisher: This article contains the abstract only.

The Nernst effect in layered superconductors under a magnetic field

2016 ◽  
Vol 30 (22) ◽  
pp. 1650281 ◽  
Author(s):  
Bui Duc Tinh ◽  
Le Minh Thu ◽  
Nguyen Quang Hoc
Keyword(s):  
Thermal Noise ◽  
Gaussian Approximation ◽  
Landau Levels ◽  
Recent Experimental Data ◽  
Type Ii ◽  
Nernst Effect ◽  
Ginzburg Landau ◽  
Type Ii Superconductor ◽  
Self Consistent ◽  
Tdgl Equation

We calculated the Nernst signal [Formula: see text], describing the Nernst effect in type-II superconductor in the vortex–liquid regime, by using the time-dependent Ginzburg–Landau (TDGL) equation with thermal noise. The nonlinear interaction term in the TDGL equation is treated within self-consistent Gaussian approximation. The expression of the Nernst signal [Formula: see text] including all the Landau levels is presented in explicit form which is applicable essentially to the whole phase. Our results are compared with the recent experimental data on high-[Formula: see text] superconductor.

ZERO-BIAS ANOMALIES IN THE CURRENT-VOLTAGE AND CONDUCTANCE-VOLTAGE CHARACTERISTICS OF HIGH-CRITICAL-TEMPERATURE SUPERCONDUCTOR JUNCTIONS

1992 ◽  
Vol 06 (02) ◽  
pp. 125-170 ◽  
Author(s):  
THOMAS WALSH
Keyword(s):  
Critical Temperature ◽  
Proximity Effects ◽  
High Critical Temperature ◽  
Normal Surface ◽  
Superconducting Layer ◽  
Zero Bias ◽  
Current Voltage ◽  
Conductive Channel ◽  
In Series ◽  
Magnetic States

The occurrence of zero-bias anomalies (ZBAs) in the current-voltage and conductance-voltage characteristics of high-critical-temperature superconductors (HTS) is reviewed. Following a historical introduction, we summarize studies noting HTS ZBAs. Several explanations of the ZBAs in HTS tunneling characteristics have been proposed including a resistance in series with a Josephson junction, a conductive channel near the Fermi energy ε F , localized magnetic states on film surfaces, proximity effects, a peak in the electron density of states near ε F , an array of junctions in an HTS ceramic sample, coupling between a film's normal surface layer and the superconducting layer below the surface, quasiparticle tunneling, and phase diffusion. The plausibility and implications of these suggested explanations are discussed. Experiments to answer questions that remain regarding the source and significance of the ZBAs are proposed.

scholarly journals Pengaruh Variasi Dimensi Superkonduktor Berbentuk Persegi Panjang Terhadap Medan Kritis Pada Pada κ = 1,5

2020 ◽  
Vol 5 ◽  
Author(s):  
Alqaan Maqbullah Ilmi ◽  
Cari Cari ◽  
Fuad Anwar
Keyword(s):  
Equilibrium State ◽  
Critical Field ◽  
Time Dependent ◽  
Type Ii ◽  
Ginzburg Landau ◽  
Rectangular Shape ◽  
Type Ii Superconductor ◽  
Tdgl Equation

<p class="AbstractEnglish"><strong>Abstract:</strong> The Time Dependent Ginzburg-Landau (TDGL) equation can be used to study the characteristics of a superconductor in the evolution of time until it reaches an equilibrium state. This study uses the ѰU method to calculate the critical field value numerically which has been tested stable and consistent. Previous research has been carried out regarding the critical field ratio of rectangular and rectangular superconductors with the same area at κ = 1.5. This research examines the variation of the dimensions of the type II superconductor with a rectangular shape, then it is found that the critical field of the Hc<sub>3</sub> surface forms a pattern that can be used to study the characteristics of the type II superconductor.</p><p class="AbstrakIndonesia"><strong>Abstrak: </strong>Persamaan Ginzburg-Landau Gayut Waktu (Time Dependent Ginzburg-Landau/TDGL) dapat digunakan untuk mempelajari karakteristik superkonduktor dalam evolusi waktu sampai mencapai keadaan setimbang. Penelitian ini menggunakan metode ѰU untuk menghitung nilai medan kritis secara numerik yang telah teruji stabil dan konsisten. Telah dilakukan penelitian sebelumnya mengenai perbandingan medan kritis superkonduktor berbentuk persegi dan persegi panjang dengan luas sama pada κ = 1,5. Dalam penelitian ini dikaji variasi dimensi superkonduktor tipe II dengan bentuk persegi panjang, kemudian didapatkan bahwa medan kritis permukaan Hc<sub>3</sub> membentuk pola yang dapat digunakan untuk mempelajari karakteristik superkonduktor tipe II.</p>

Proximity effect enhancement induced by a superconducting anti-dot

2014 ◽  
Vol 28 (31) ◽  
pp. 1450242
Author(s):  
Sindy J. Higuera ◽  
Miryam R. Joya ◽  
J. Barba-Ortega
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Proximity Effect ◽  
Magnetization Curve ◽  
Order Parameter ◽  
Proximity Effects ◽  
Time Dependent ◽  
Critical Fields ◽  
Ginzburg Landau ◽  
Ginzburg Landau Equations

In this work, we study the proximity and pinning effects of a rectangular superconducting anti-dot on the magnetization curve of a mesoscopic sample. We solve the nonlinear time-dependent Ginzburg–Landau equations for a superconducting rectangle in the presence of a magnetic field applied perpendicular to its surface. The pinning effects are determined by the number of vortices into the anti-dot. We calculate the order parameter, vorticity, magnetization and critical fields as a function of the external magnetic field. We found that the size and nature of the anti-dot strongly affect the magnetization of the sample. The results are discussed in framework of pinning and proximity effects in mesoscopic systems.

Nonlinear dynamic properties of disk-bolt rotor with interfacial cutting faults on assembly surfaces

2017 ◽  
Vol 24 (19) ◽  
pp. 4369-4382
Author(s):  
Yi Liu ◽  
Heng Liu ◽  
BoWen Fan
Keyword(s):  
Nonlinear Dynamic ◽  
Dynamic Properties ◽  
Dynamic Balance ◽  
Three Dimensional ◽  
Rotor System ◽  
Contact Algorithm ◽  
Mass Eccentricity ◽  
Specific Shape ◽  
Nonlinear Dynamic Properties ◽  
Coupling Characteristics

Interfacial cutting faults on assembly surfaces are considered in a three-dimensional (3D) disk-bolt rotor system. The traditional finite element method is used to establish the 3D model of faulted disk-bolt rotor. A contact algorithm is applied to calculate the static features of this combined rotor. It is revealed that interfacial cutting faults produce rotor bending which is gradually strengthened as rotational speed increases besides disk’s mass eccentricity. The 3D dynamic equations of a faulted disk-bolt rotor system include these cutting faults’ static influences. The nonlinear dynamic properties are investigated by Poincaré mapping, Newton iteration and a prediction-correction algorithm. As a result, the rotor bending due to cutting faults reduces the global stability of the complicated rotor and enlarges the vibration amplitude obviously. This speed-variant bending also decides the feature that rotor vibration increases again after critical speed no matter whether dynamic balance is carried out. The maximum allowable fault depth is obtained and it gives an explanation as to why the machining precision of assembly surfaces should be strictly controlled in the disk-bolt rotor. Generally, this paper originally tries to provide a feasible approach to consider a 3D interfacial cutting fault with specific shape and to analyze the static–dynamic coupling characteristics for a disk-bolt rotor.

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