scholarly journals Static charge-density-wave order in the superconducting state of La2−xBaxCuO4

2017 ◽  
Vol 95 (24) ◽  
Author(s):  
V. Thampy ◽  
X. M. Chen ◽  
Y. Cao ◽  
C. Mazzoli ◽  
A. M. Barbour ◽  
...  
Keyword(s):  
Charge Density ◽  
Superconducting State ◽  
Charge Density Wave ◽  
Density Wave ◽  
Static Charge

scholarly journals Interpretations of ground-state symmetry breaking and strong correlation in wavefunction and density functional theories

2021 ◽  
Vol 118 (4) ◽  
pp. e2017850118 ◽  
Author(s):  
John P. Perdew ◽  
Adrienn Ruzsinszky ◽  
Jianwei Sun ◽  
Niraj K. Nepal ◽  
Aaron D. Kaplan
Keyword(s):  
Density Functional Theory ◽  
Charge Density ◽  
Ground State ◽  
Charge Density Wave ◽  
Density Functional ◽  
Density Wave ◽  
Static Charge ◽  
Functional Theory ◽  
Correlation Kernel ◽  
Frequency Moments

Strong correlations within a symmetry-unbroken ground-state wavefunction can show up in approximate density functional theory as symmetry-broken spin densities or total densities, which are sometimes observable. They can arise from soft modes of fluctuations (sometimes collective excitations) such as spin-density or charge-density waves at nonzero wavevector. In this sense, an approximate density functional for exchange and correlation that breaks symmetry can be more revealing (albeit less accurate) than an exact functional that does not. The examples discussed here include the stretched H2 molecule, antiferromagnetic solids, and the static charge-density wave/Wigner crystal phase of a low-density jellium. Time-dependent density functional theory is used to show quantitatively that the static charge-density wave is a soft plasmon. More precisely, the frequency of a related density fluctuation drops to zero, as found from the frequency moments of the spectral function, calculated from a recent constraint-based wavevector- and frequency-dependent jellium exchange-correlation kernel.

d-wave pairing in the doped static charge-density-wave state on a two-dimensional square lattice

2000 ◽  
Vol 62 (14) ◽  
pp. 9648-9653 ◽  
Author(s):  
Mikio Onozawa ◽  
Yoshiyuki Fukumoto ◽  
Akihide Oguchi ◽  
Yukio Mizuno
Keyword(s):  
Charge Density ◽  
Charge Density Wave ◽  
Density Wave ◽  
Square Lattice ◽  
Two Dimensional ◽  
Static Charge ◽  
Wave State ◽  
Wave Pairing ◽  
D Wave

scholarly journals Colossal Magnetoresistance in Ln1-x Ax MnO3 Perovskites

1999 ◽  
Vol 52 (2) ◽  
pp. 155 ◽  
Author(s):  
J. B. Goodenough
Keyword(s):  
Magnetic Field ◽  
Charge Density ◽  
Applied Magnetic Field ◽  
Charge Density Wave ◽  
Colossal Magnetoresistance ◽  
Density Wave ◽  
Orthorhombic Phase ◽  
Orbital Ordering ◽  
Static Charge ◽  
O Phase

In the Ln1-xAxMnO3 pseudoperovskites in which Ln is a lanthanide and A an alkaline-earth atom, an intrinsic colossal magnetoresistance (CMR) occurs in an O-orthorhombic phase near an O′-orthorhombic/O-orthorhombic phase boundary. For a fixed ratio Mn(IV)/Mn = 0·3, the transition through the O phase from localised-electron behaviour and orbital ordering in the O′ phase to itinerant-electron behaviour in an R-rhombohedral phase occurs with increasing geometric tolerance factor t ≡ ⟨A-O⟩/√2⟨Mn-O⟩, where ⟨A-O⟩ and ⟨Mn-O⟩ are mean equilibrium bond lengths. The CMR occurs in the temperature interval Tc ≤ T < Ts where there is a segregation, via cooperative oxygen displacements, into a Mn(IV)-rich ferromagnetic phase imbedded in a paramagnetic phase. The volume of the ferromagnetic, more conductive clusters increases from below to beyond a percolation threshold in response, above Tc, to an applied magnetic field and, below Tc, to a Weiss molecular field. In the O phase, the magnetic transition at Tc decreases on the exchange of 18O/16O and increases under hydrostatic pressure. Charge and orbital ordering below a Tco ≤ Tc is found in compositions with x ≈ ⅛ or x ≈ ½. With x ≈ ½, the charge-ordered phase CE is tetragonal and antiferromagnetic. An applied magnetic field stabilises the ferromagnetic, conductive phase relative to the insulator phase CE to give a second type of intrinsic CMR. For x ≈ 0·3, there is no static charge and orbital ordering; but for smaller t, strong electron-lattice coupling gives a ‘bad metal’ behaviour below Tc indicative of a dynamic phase segregation as in a traveling charge-density wave. In La1-xCaxMnO3 with ½ ≤ x ≤ ⅞, segregation of the CE x = 0·5 phase and the all-Mn(IV) x = 1 phase has been reported to take the form of a static charge-density wave. The origins of this complex behaviour are discussed.

Incommensurate modulated phases of the NbxTa1-xTe4 charge density wave system

1992 ◽  
Vol 50 (1) ◽  
pp. 58-59
Author(s):  
S. Ritchie ◽  
J. C. Bennett ◽  
A. Prodan ◽  
F.W. Boswell ◽  
J.M. Corbett
Keyword(s):  
Charge Density ◽  
Charge Density Wave ◽  
Direct Evidence ◽  
Density Wave ◽  
Wave System ◽  
Modulated Phases ◽  
Metal Atoms ◽  
Incommensurate Modulation ◽  
End Members ◽  
Modulation Wave Vector

A continuous sequence of compounds having composition NbxTa1-xTe4; 0 ≤ x ≤ 1 have been studied by electron diffraction and microscopy. Previous studies have shown that the end members of the series, TaTε4 and NbTε4 possess a quasi-one-dimensional character and exhibit charge density wave (CDW) distortions. In these compounds, the subcell structure is tetragonal with axes (a × a × c) and consists of the metal atoms (Nb or Ta) centered within an extended antiprismatic cage of Te atoms. At room temperature, TaTε4 has a commensurate modulation structure with a 2a × 2a × 3c unit cell. In NbTε4, an incommensurate modulation with × ∼ 16c axes is observed. Preliminary studies of the mixed compounds NbxTα1-xTε4 showed a discontinuous jump of the modulation wave vector commensurate to incommensurate when the Nb dopant concentration x, exceeded x ≃ 0.3, In this paper, the nature of the compositional dependence of is studied in greater detail and evidence is presented for a stepwise variation of . This constitutes the first direct evidence for a Devil's staircase in CDW materials.

Wave Analysis of the Charge Density Wave Dynamics in the Molecular Conductor (Perylene)2Pt(mnt)2 (mnt=maleonitriledithiolate)

1995 ◽  
Vol 5 (5) ◽  
pp. 539-545 ◽  
Author(s):  
J. Dumas ◽  
N. Thirion ◽  
M. Almeida ◽  
E. B. Lopes ◽  
M. J. Matos ◽  
...  
Keyword(s):  
Charge Density ◽  
Charge Density Wave ◽  
Density Wave ◽  
Wave Analysis ◽  
Wave Dynamics ◽  
Molecular Conductor
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