NONPHONON MECHANISM OF SUPERCONDUCTIVITY IN COMPOUNDS OF TRANSITION METALS

1989 ◽  
Vol 03 (09) ◽  
pp. 1403-1423 ◽  
Author(s):  
V.A. IVANOV ◽  
R.O. ZAITSEV
Keyword(s):  
Magnetic Field ◽  
Relaxation Time ◽  
Transition Metals ◽  
Superconducting State ◽  
Ground State ◽  
Weak Magnetic Field ◽  
State Energy ◽  
Landau Equation ◽  
Ginzburg Landau ◽  
Mechanism Of Superconductivity

The kinematical mechanism of superconductivity is applied to the Emery-Hirsch model for the CuO 2 and BiO 3 layers. A superconducting region due to strong kinematic interaction of p- and s, d-electrons are determined as a function of np and ns,d-degrees of non-filling of 2p6, 6s2, 3d10 shells of O 2−, Bi 3+, Cu +. The T c is calculated taking into account the spin flip relaxation time. Magnetostatic properties of a superconducting state in a weak magnetic field are investigated. Coefficients of the Ginzburg-Landau equation are calculated. The ground state energy of the Emery-Hirsch model is also calculated.

scholarly journals A perturbation theory approach to the ground state exciton energy in the limit of a weak magnetic field in anomalous exciton Hall effect

2021 ◽  
Vol 2015 (1) ◽  
pp. 012135
Author(s):  
V A Shabashov ◽  
V K Kozin ◽  
A V Kavokin ◽  
I A Shelykh
Keyword(s):  
Magnetic Field ◽  
Perturbation Theory ◽  
Dipole Moment ◽  
External Magnetic Field ◽  
Hall Effect ◽  
Ground State ◽  
Weak Magnetic Field ◽  
State Energy ◽  
Theory Approach ◽  
Exciton Energy

Abstract The anomalous exciton Hall effect is a phenomenon that occurs in a quantum well in the presence of an external magnetic field applied perpendicular to the surface due to the interaction of the exciton dipole moment with an electric field, formed by the charged impurities. The effect was fully described in [1] for different magnetic field regimes. In this paper, we focus on the way the perturbation method was used for finding the ground state energy of an exciton in the limit of a weak magnetic field.

ON CALCULATION OF ENERGY OF PLANAR LATTICE FERMIONS IN A MAGNETIC FIELD

1990 ◽  
Vol 04 (10) ◽  
pp. 689-696 ◽  
Author(s):  
A. G. ABANOV ◽  
D. V. KHVESHCHENKO
Keyword(s):  
Magnetic Field ◽  
Ground State ◽  
Weak Magnetic Field ◽  
State Energy ◽  
Modern Theory ◽  
Strongly Correlated ◽  
Planar Lattice ◽  
Fermionic Systems ◽  
Small Density ◽  
Lattice Fermions

We calculate the energy of lattice fermions with a small density moving in a weak magnetic field. It is shown that the ground state energy has a minimum at B = 2πν/ea2. Based on this fact we discuss some aspects of the modern theory of strongly correlated fermionic systems.

TIGHT-BINDING MODEL FOR THE QUANTUM LADDER IN A MAGNETIC FIELD

1996 ◽  
Vol 10 (28) ◽  
pp. 3827-3856 ◽  
Author(s):  
KAZUMOTO IGUCHI
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Ground State Energy ◽  
Ground State ◽  
State Energy ◽  
Tight Binding ◽  
Critical Value ◽  
Tight Binding Model ◽  
Binding Model ◽  
First Case

A tight-binding model is formulated for the calculation of the electronic structure and the ground state energy of the quantum ladder under a magnetic field, where the magnetic flux at the nth plaquette is given by ϕn. First, the theory is applied to obtain the electronic spectra of the quantum ladder models with particular magnetic fluxes such as uniform magnetic fluxes, ϕn=0 and 1/2, and the staggered magnetic flux, ϕn= (−1)n+1ϕ0. From these, it is found that as the effect of electron hopping between two chains—the anisotropy parameter r=ty/tx—is increased, there are a metal-semimetal transition at r=0 and a semimetal–semiconductor transition at r=2 in the first case, and metal-semiconductor transitions at r=0 in the second and third cases. These transitions are thought of as a new category of metal-insulator transition due to the hopping anisotropy of the system. Second, using the spectrum, the ground state energy is calculated in terms of the parameter r. It is found that the ground state energy in the first case diverges as r becomes arbitrarily large, while that in the second and third cases can have the single or double well structure with respect to r, where the system is stable at some critical value of r=rc and the transition between the single and double well structures is associated with whether tx is less than a critical value of txc. The latter cases are very reminiscent of physics in polyacetylene studied by Su, Schrieffer and Heeger.

HIGH FIELD PHASE DIAGRAM OF THE FIELD-INDUCED SUPERCONDUCTING STATE OF λ-(BETS)2FeCl4

2002 ◽  
Vol 16 (20n22) ◽  
pp. 3101-3104
Author(s):  
L. BALICAS ◽  
J. S. BROOKS ◽  
K. STORR ◽  
S. UJI ◽  
M. TOKUMOTO ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Superconducting State ◽  
Ground State ◽  
Electrical Transport ◽  
High Field ◽  
Two Dimensional ◽  
Exchange Field ◽  
Organic Conductor ◽  
Field Phase ◽  
Antiferromagnetic Ground State

We investigate by electrical transport the field-induced superconducting state (FISC) in the organic conductor λ- (BETS) 2 FeCl 4. Below 4 K, antiferromagnetic-insulator, metallic, and eventually superconducting (FISC) ground states are observed with increasing in-plane magnetic field. The FISC state survives between 18 and 41 T, and can be interpreted in terms of the Jaccarino-Peter effect, where the external magnetic field compensates the exchange field of aligned Fe 3+ ions. We further argue that the Fe 3+ moments are essential to stabilize the resulting singlet, two-dimensional superconducting state. Here we provide experimental evidence indicating that this state, as well as the insulating antiferromagnetic ground state, is extremely sensitive to hydrostatic pressure.

scholarly journals Weakly Nonlinear Magnetic Convection in a Nonuniformly Rotating Electrically Conductive Medium Under the Action of Modulation of External Fields

2020 ◽  
Keyword(s):  
Magnetic Field ◽  
Angular Velocity ◽  
Landau Equation ◽  
Temperature Modulation ◽  
External Fields ◽  
Ginzburg Landau ◽  
Electrically Conductive ◽  
Weakly Nonlinear ◽  
Conductive Fluid ◽  
Ginzburg Landau Equations

In this paper we studied the weakly nonlinear stage of stationary convective instability in a nonuniformly rotating layer of an electrically conductive fluid in an axial uniform magnetic field under the influence of: a) temperature modulation of the layer boundaries; b) gravitational modulation; c) modulation of the magnetic field; d) modulation of the angular velocity of rotation. As a result of applying the method of perturbation theory for the small parameter of supercriticality of the stationary Rayleigh number nonlinear non-autonomous Ginzburg-Landau equations for the above types of modulation were obtaned. By utilizing the solution of the Ginzburg-Landau equation, we determined the dynamics of unsteady heat transfer for various types of modulation of external fields and for different profiles of the angular velocity of the rotation of electrically conductive fluid.

The influences of parabolic potential and magnetism on strongly coupled polaron characteristics within asymmetric Gaussian quantum wells

2021 ◽  
Author(s):  
Saren Gaowa ◽  
Yan-Bo Geng ◽  
Zhao-Hua Ding ◽  
Jing-Lin Xiao
Keyword(s):  
Magnetic Field ◽  
Quantum Wells ◽  
Barrier Height ◽  
Ground State Energy ◽  
Ground State ◽  
State Energy ◽  
Cyclotron Frequency ◽  
Strongly Coupled ◽  
Parabolic Potential ◽  
Do So

In this research, the effects of magnetism and parabolic potential on strongly coupled polaron characteristics within asymmetric Gaussian quantum wells (AGQWs) were investigated. To do so, the following six parameters were studied, temperature, AGQW barrier height, Gaussian confinement potential (GCP) width, confinement strengths along the directions of [Formula: see text] and [Formula: see text], as well as magnetic field cyclotron frequency. The relationships among frequency oscillation, AGQW parameters and polaron ground state energy in RbCl crystal were studied based on linear combination operator and Lee–Low–Pines unitary transformation. It was concluded that ground state energy absolute value was decreased by increasing GCP width and temperature, and increased with the increase of confinement strength along [Formula: see text] and [Formula: see text] directions, cyclotron frequency of magnetic field and barrier height of AGQW. It was also found that vibrational frequency was increased by enhancing confinement strengths along the directions of [Formula: see text] and [Formula: see text], magnetic field cyclotron frequencies, barrier height AGQW and temperature and decreased with the increase of GCP width.

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