Application of Bogoliubov-de Gennes equations to vortices in Hubbard superconductors

2015 ◽  
Vol 1753 ◽  
Author(s):  
Chumin Wang ◽  
César G. Galván ◽  
Luis A. Pérez
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
Electron Concentration ◽  
Nearest Neighbor ◽  
Magnetic Vortex ◽  
Superconducting Gap ◽  
Electronic Specific Heat ◽  
Neighbor Interaction ◽  
Self Consistent ◽  
Generalized Hubbard Model

ABSTRACTIn this work, the formation of d-wave superconducting magnetic vortex is studied within the Bogoliubov-de Gennes formalism and the generalized Hubbard model, which leads to 2N2 coupled self-consistent equations for a supercell of N×N atoms. These equations determine the spatial variation of the superconducting gap as a function of the electron concentration and electron-electron interactions. The results show that the superconducting states induced by the correlated hopping (Δt3) are more sensitive to the presence of magnetic field than those induced by attractive nearest-neighbor interaction (V). Furthermore, we calculate the electronic specific heat as a function of the temperature for a given applied magnetic field, whose behavior has a qualitative agreement with experimental data.

COMPENSATION TEMPERATURE OF A MIXED SPIN-1 AND SPIN-1/2 HEISENBERG FERRIMAGNETIC MODEL

2004 ◽  
Vol 18 (10n11) ◽  
pp. 1637-1649 ◽  
Author(s):  
JUN LI ◽  
GUOZHU WEI ◽  
AN DU
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Crystal Field ◽  
Nearest Neighbor ◽  
Magnetic Behavior ◽  
Compensation Temperature ◽  
Square Lattice ◽  
Function Technique ◽  
Neighbor Interaction ◽  
Mixed Spin

The behavior of the compensation of a mixed spin-1 and spin-1/2 Heisenberg ferrimagnetic system on a square lattice is investigated theoretically by a two-time Green-function technique which takes into account the quantum nature of Heisenberg spins. The model includes the nearest and next-nearest neighbor interactions between spins, a crystal field and an external magnetic field. This model can be relevant for understanding the magnetic behavior of bimetallic molecular ferrimagnets that are currently being synthesized by several experimental groups. We study the spin-wave spectra of the ground state and investigate the effects of the next-nearest neighbor interactions, a crystal field and an external magnetic field on the compensation temperature. It is found that a compensation point appears and it is basically unchanged when the next-nearest-neighbor interaction between spin-1/2 is taken into account and exceeds a minimum value for other values in Hamiltonian fixed. The compensation temperature is influenced by the next-nearest-neighbor interaction between spin-1 and the external magnetic field and it is disappearing as these parameters exceed the trivial values.

SIMULATION OF A MULTICRITICAL FCC ISING ANTIFERROMAGNET

1996 ◽  
Vol 07 (06) ◽  
pp. 857-861
Author(s):  
D. RENNÉ
Keyword(s):  
Magnetic Field ◽  
Monte Carlo ◽  
External Magnetic Field ◽  
Triple Point ◽  
Nearest Neighbor ◽  
Neighbor Interaction ◽  
Multicritical Point ◽  
Fcc Lattice ◽  
Ising Antiferromagnet ◽  
Open Question

Inspired by the work by Kämmerer, Dünweg, Binder, and d'Onorio de Meo we investigated the spin-[Formula: see text] Ising antiferromagnet on a fcc lattice in a homogeneous external magnetic field H with uniform nearest-neighbor interaction J by Monte Carlo simulations. In order to answer the open question whether this system exhibits a triple point or a multicritical point for positive H, we mainly studied lattices with 4 · 323 and 4 · 723 spins. We found a multicritical point at (Hc, kBTc) = (3.49 ± 0.02, 1.02 ± 0.01) J in the thermodynamic limit.

Entanglement and quantum spin glass

2014 ◽  
Vol 28 (20) ◽  
pp. 1430012 ◽  
Author(s):  
C. Y. Koh
Keyword(s):  
Magnetic Field ◽  
Spin Glass ◽  
General Formula ◽  
Nearest Neighbor ◽  
Quantum Spin ◽  
Neighbor Interaction ◽  
Qubit System ◽  
J Coupling ◽  
Xx Model ◽  
Heisenberg Xx Model

The paper reviews the entanglement behavior of a 2-qubit system in a quantum spin glass using the Heisenberg XX model and the interaction of the system with a spin glass bath environment. In the first part, we study the entanglement (concurrence) for a 3- and 4-qubit with nearest neighbor interaction. With a fixed mean and varying standard deviation for the J coupling, the concurrence is numerically plotted with temperature for the different configurations. A general formula for the concurrence is given for n qubits at low temperature. In the second part, we study the concurrence of a 2-qubit system coupled to a spin glass bath environment with n = 2 to ≥ 4 qubits. The bath sites are coupled with random J coupling and varying applied magnetic field. A general formula for concurrence is given for mean J = 0 and B = 0 for n bath sites. For small random J and magnetic field B, a steady state is obtained with an approximate concurrence of 0.5, showing that the entanglement is preserved.

The Role of Next-Nearest Neighbors in The Neel Model of Surface Anisotropy for BCC Crystals

1991 ◽  
Vol 231 ◽  
Author(s):  
Robert L. White ◽  
Bruce M. Clemens
Keyword(s):  
Experimental Data ◽  
Thin Films ◽  
Nearest Neighbor ◽  
Nearest Neighbors ◽  
Surface Anisotropy ◽  
Neighbor Interaction ◽  
Dominant Source ◽  
Cast Doubt

AbstractWe have extended the Neél model of surface anisotropy in b.c.c. crystals to include next nearest neighbor interaction. Fitting the experimental data for Fe (001) and (110) surfaces leads to some pradoxes which cast doubt on the Neél surface anisotropy as the dominant source of surface anisotropy in thin films.

A New Condition of Formation and Stablity of All Crystalline Systems in a Good Agreement with Experimental Data

2015 ◽  
Vol 11 (3) ◽  
pp. 3224-3228
Author(s):  
Tarek El-Ashram
Keyword(s):  
Experimental Data ◽  
Brillouin Zone ◽  
Electron Concentration ◽  
Free Electron ◽  
Lattice Point ◽  
Valence Electron ◽  
Fermi Gas ◽  
Valence Electron Concentration ◽  
Fermi Sphere ◽  
Good Agreement

In this paper we derived a new condition of formation and stability of all crystalline systems and we checked its validity andit is found to be in a good agreement with experimental data. This condition is derived directly from the quantum conditionson the free electron Fermi gas inside the crystal. The new condition relates both the volume of Fermi sphere VF andvolume of Brillouin zone VB by the valence electron concentration VEC as ;𝑽𝑭𝑽𝑩= 𝒏𝑽𝑬𝑪𝟐for all crystalline systems (wheren is the number of atoms per lattice point).

scholarly journals A Magneto-Active Elastomer Crawler with Peristaltic and Caterpillar Locomotion Patterns

Actuators ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 74
Author(s):  
Tsam Lung You ◽  
Hemma Philamore ◽  
Fumitoshi Matsuno
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
External Magnetic Field ◽  
Mathematical Models ◽  
Confined Spaces ◽  
Low Mass ◽  
Structural Simplicity

In this work we present a soft crawler fabricated using a magneto-active elastomer. The crawler is controlled by an external magnetic field to produce two locomotion patterns: peristaltic and caterpillar crawling. Due to its structural simplicity, low mass, wirelessly controlled actuation and compliant body the design of this crawler has the potential to address the key challenges faced by existing crawling robots. Experimental data were gathered to evaluate the performance of the crawler locomotion in a pipe. The results validated the mathematical models proposed to estimate the distance traveled by the crawler. The crawler shows potential for use in exploration of confined spaces.

Sign in / Sign up

Export Citation Format

Share Document