The new features of generalized order parameter localization in multi-layered magnetic structures

2021 ◽  
pp. 2150201
Author(s):  
S. E. Savotchenko
Keyword(s):  
Order Parameter ◽  
Density Wave ◽  
Spin Density Wave ◽  
Nonlinear Effects ◽  
Analytical Form ◽  
Localized States ◽  
Local Magnetization ◽  
Dispersion Equations ◽  
Localized State ◽  
Generalized Order

The new types of nonlinear localized state of generalized order parameter in the three-layered structure of band antiferromagnets with congruent sections of the Fermi surface are obtained. The nonlinear effects inside the narrow plane defects between the layers representing the local magnetization in the direction of polarization of the spin density wave are described by the nonlinear source function. The variation of the Ginsburg–Landau functional near the Lifshitz point leads to nonlinear Schrödinger equation (NSE) with cubic nonlinear terms and self-consistent nonlinear potential modeling the plane defects. The dispersion equations of two type stationary nonlinear localized states are derived. The solutions of dispersion equations in explicit analytical form in dependence on characteristics of plane defects and the distance between them are found and analyzed. The localized states of order parameter existing only near the plane defects with nonlinear response are obtained.

scholarly journals Relationship between the elastic properties and the order parameter of the spin-density wave phase of (TMTSF)2PF6

1993 ◽  
Vol 03 (C2) ◽  
pp. C2-225-C2-230
Author(s):  
S. E. BROWN ◽  
B. ALAVI ◽  
W. G. CLARK ◽  
M. E. HANSON ◽  
B. KLEMME
Keyword(s):  
Spin Density ◽  
Elastic Properties ◽  
Order Parameter ◽  
Density Wave ◽  
Spin Density Wave ◽  
Wave Phase

scholarly journals Negative Energy Antiferromagnetic Instantons Forming Cooper-Pairing ‘Glue’ and ‘Hidden Order’ in High-Tc Cuprates

2018 ◽  
Vol 3 (4) ◽  
pp. 39 ◽  
Author(s):  
Sergei Mukhin
Keyword(s):  
Spin Density ◽  
High Temperature Superconductivity ◽  
Density Wave ◽  
Spin Density Wave ◽  
Mean Field ◽  
Analytical Form ◽  
Negative Energy ◽  
Cooper Pairing ◽  
Hidden Order ◽  
The Green Function

An emergence of magnetic boson of instantonic nature, that provides a Cooper-‘pairing glue’, is considered in the repulsive ‘nested’ Hubbard model of superconducting cuprates. It is demonstrated that antiferromagnetic instantons of a spin density wave type may have negative energy due to coupling with Cooper pair condensate. A set of Eliashberg like equations is derived and solved self-consistently, proving the above suggestion. An instantonic propagator plays the role of the Green function of the pairing ‘glue’ boson. Simultaneously, the instantons defy condensation of the mean-field spin-density wave (SDW) order. We had previously demonstrated in analytical form that periodic chain of instanton-anti-instanton pairs along the axis of Matsubara time has zero scattering cross section for weakly perturbing external probes, like neutrons, etc., thus representing a ‘hidden order’. Hence, the two competing orders, superconducting and antiferromagnetic, may coexist (below some T c ) in the form of the superconducting order coupled to ‘hidden’ instantonic one. This new picture is discussed in relation with the mechanism of high temperature superconductivity.

What is the Symmetry of the High-Tc Order Parameter?

1998 ◽  
Vol 12 (29n31) ◽  
pp. 2920-2931 ◽  
Author(s):  
Richard A. Klemm
Keyword(s):  
High Temperature ◽  
Order Parameter ◽  
High Temperature Superconductors ◽  
Density Wave ◽  
Spin Density Wave ◽  
Superconducting Gap ◽  
S Wave ◽  
Orbital Symmetry ◽  
High Tc ◽  
Phase Sensitive

In recent years, there has been a raging controversy regarding the orbital symmetry of the superconducting order parameter (OP) in the high temperature superconductors. Many experiments were interpreted in terms of a dx2-y2-wave OP, but many others were interpreted in terms of a more conventional s-wave OP. We review the problems of both intrinsic and extrinsic natures with the phase-sensitive experiments on YBCO. We further show that the photoemission experiments of the purported superconducting gap in Bi2Sr2CaCu2O 8+δ are entirely consistent with charge- and/or spin-density wave formation in that material. The presence of such density waves greatly complicates the analysis of most experiments. Hence, we conclude that the orbital symmetry of the superconducting OP is still unknown in any of the high temperature superconductors.

PECULIARITIES OF ELECTRONIC PARAMAGNETISM IN ANTIFERROMAGNETS

1989 ◽  
Vol 03 (12) ◽  
pp. 945-948
Author(s):  
S. BRAZOVSKII ◽  
I. LUKJANCHUK ◽  
R. RAMAZASHVILI
Keyword(s):  
Magnetic Field ◽  
Spin Density ◽  
Density Wave ◽  
Spin Density Wave ◽  
Electronic States ◽  
Localized States ◽  
Zone Boundary ◽  
Superconducting Cuprates ◽  
The Magnetic Field

The continuous and localized states of electrons in antiferromagnets (AFM) are studied in the presence of the magnetic field or the intrinsic magnetization. Peculiar features of both the Pauli and Curie susceptibilities are found. They may be tested in all intrinsic AFM with residual carriers like spin density wave (SDW) compounds, superconducting cuprates and also in s-f systems if their relevant electronic states are close to the reduced magnetic zone boundary (MZB).

SPIN FLUCTUATION THEORY FOR TEMPERATURE-INDUCED FERROMAGNETISM IN ITINERANT ANTIFERROMAGNETS AND PARAMAGNETS

1995 ◽  
Vol 09 (10) ◽  
pp. 1171-1184 ◽  
Author(s):  
A.A. POVZNER ◽  
D.V. LIKHACHEV
Keyword(s):  
Order Parameter ◽  
Magnetic Phase ◽  
Spin Fluctuation ◽  
Density Wave ◽  
Spin Density Wave ◽  
Spin Fluctuations ◽  
Fluctuation Theory ◽  
Itinerant Electron ◽  
Electron Systems ◽  
Antiferromagnetic Transition

The possible occurrence of “temperature-induced ferromagnetism” in itinerant antiferromagnets with spin-density wave and strong paramagnets is discussed on the basis of spin fluctuation theory taking account of the effect of large ferromagnetic spin fluctuations. It is shown that the presence of a point of inflexion of the density of states near the Fermi level leads to the appearance of temperature-induced ferromagnetic order parameter in the itinerant electron systems. In addition the influence of this order parameter on the antiferromagnetic transition temperature is demonstrated and new mechanism of the magnetic phase transition is studied in relation to the magnetism of TiBe 2.

PSEUDOGAP PHENOMENA AND THE DENSITY WAVES IN HIGH-Tc CUPRATES

2001 ◽  
Vol 15 (32) ◽  
pp. 4161-4171 ◽  
Author(s):  
ANGSULA GHOSH
Keyword(s):  
Order Parameter ◽  
Cuprate Superconductors ◽  
Nearest Neighbor ◽  
Density Wave ◽  
Tight Binding ◽  
Spin Density Wave ◽  
Mean Field ◽  
Field Calculation ◽  
Density Waves ◽  
Binding Model

We consider the density waves as possible explanations for the pseudogap in high temperature cuprate superconductors. Both the conventional spin density wave (SDW) and the unconventional d-density waves are considered in our study using a mean-field calculation of the tight binding model including terms upto second nearest neighbor hopping (γ). The phase diagrams for the order parameter and temperature with doping in the above types of density waves are discussed. The d-SDW does not coexist with the superconducting gap when studied with doping whereas the d-charge density wave (DDW) shows a state of coexistence. The temperature dependence of the order parameter and specific heat is also demonstrated. The spectral function of the SDW is also considered for various temperatures and doping.

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