Magnetic Field Induced Transitions from Spin Glass to Liquid to Long Range Order in a 3D Geometrically Frustrated Magnet

1999 ◽  
Vol 82 (17) ◽  
pp. 3532-3535 ◽  
Author(s):  
Y. K. Tsui ◽  
C. A. Burns ◽  
J. Snyder ◽  
P. Schiffer
Keyword(s):  
Magnetic Field ◽  
Spin Glass ◽  
Long Range ◽  
Range Order ◽  
Long Range Order ◽  
Geometrically Frustrated ◽  
Frustrated Magnet

Superfluidity and Superconductivity

2018 ◽  
Author(s):  
Norman J. Morgenstern Horing
Keyword(s):  
Magnetic Field ◽  
Wave Function ◽  
Wave Packet ◽  
Long Range ◽  
Cooper Pair ◽  
Bose Condensation ◽  
Range Order ◽  
Condensed State ◽  
Long Range Order ◽  
Coherent Wave

Chapter 13 addresses Bose condensation in superfluids (and superconductors), which involves the field operator ψ‎ having a c-number component (<ψ(x,t)>≠0), challenging number conservation. The nonlinear Gross-Pitaevskii equation is derived for this condensate wave function<ψ>=ψ−ψ˜, facilitating identification of the coherence length and the core region of vortex motion. The noncondensate Green’s function G˜1(1,1′)=−i<(ψ˜(1)ψ˜+(1′))+> and the nonvanishing anomalous correlation function F˜∗(2,1′)=−i<(ψ˜+(2)ψ˜+(1′))+> describe the dynamics and elementary excitations of the non-condensate states and are discussed in conjunction with Landau’s criterion for viscosity. Associated concepts of off-diagonal long-range order and the interpretation of <ψ> as a superfluid order parameter are also introduced. Anderson’s Bose-condensed state, as a phase-coherent wave packet superposition of number states, resolves issues of number conservation. Superconductivity involves bound Cooper pairs of electrons capable of Bose condensation and superfluid behavior. Correspondingly, the two-particle Green’s function has a term involving a product of anomalous bound-Cooper-pair condensate wave functions of the type F(1,2)=−i<(ψ(1)ψ(2))+>≠0, such that G2(1,2;1′,2′)=F(1,2)F+(1′,2′)+G˜2(1,2;1′,2′). Here, G˜2 describes the dynamics/excitations of the non-superfluid-condensate states, while nonvanishing F,F+ represent a phase-coherent wave packet superposition of Cooper-pair number states and off-diagonal long range order. Employing this form of G2 in the G1-equation couples the condensed state with the non-condensate excitations. Taken jointly with the dynamical equation for F(1,2), this leads to the Gorkov equations, encompassing the Bardeen–Cooper–Schrieffer (BCS) energy gap, critical temperature, and Bogoliubov-de Gennes eigenfunction Bogoliubons. Superconductor thermodynamics and critical magnetic field are discussed. For a weak magnetic field, the Gorkov-equations lead to Ginzburg–Landau theory and a nonlinear Schrödinger-like equation for the pair wave function and the associated supercurrent, along with identification of the Cooper pair density. Furthermore, Chapter 13 addresses the apparent lack of gauge invariance of London theory with an elegant variational analysis involving re-gauging the potentials, yielding a manifestly gauge invariant generalization of the London equation. Consistency with the equation of continuity implies the existence of Anderson’s acoustic normal mode, which is supplanted by the plasmon for Coulomb interaction. Type II superconductors and the penetration (and interaction) of quantized magnetic flux lines are also discussed. Finally, Chapter 13 addresses Josephson tunneling between superconductors.

Breakup of long-range order in the diluted antiferromagnetK2MnxZn1−xF4in zero magnetic field

1987 ◽  
Vol 35 (13) ◽  
pp. 7157-7160 ◽  
Author(s):  
C. Dekker ◽  
A. F. M. Arts ◽  
H. W. de Wijn ◽  
J. K. Kjems
Keyword(s):  
Magnetic Field ◽  
Long Range ◽  
Range Order ◽  
Zero Magnetic Field ◽  
Long Range Order

Evolution from long-range order to spin glass state in Heisenberg antiferromagnetic alloys of γ-Fe

1993 ◽  
Vol 118 (1-2) ◽  
pp. 77-85 ◽  
Author(s):  
G.A. Takzei ◽  
A.B. Surzhenko ◽  
I.I. Sych ◽  
M.V. Gavrilenko ◽  
Yu.P. Grebenyuk ◽  
...  
Keyword(s):  
Spin Glass ◽  
Long Range ◽  
Range Order ◽  
Spin Glass State ◽  
Long Range Order ◽  
Glass State

scholarly journals Juxtaposition of spin freezing and long range order in a series of geometrically frustrated antiferromagnetic gadolinium garnets

2013 ◽  
Vol 87 (17) ◽  
Author(s):  
J. A. Quilliam ◽  
S. Meng ◽  
H. A. Craig ◽  
L. R. Corruccini ◽  
G. Balakrishnan ◽  
...  
Keyword(s):  
Long Range ◽  
Range Order ◽  
Long Range Order ◽  
Geometrically Frustrated ◽  
Spin Freezing

Spin-glass-like behaviour and long-range order in dilute YTb alloys

1985 ◽  
Vol 55 (3) ◽  
pp. 237-239 ◽  
Author(s):  
L.J.P Ketelsen ◽  
M.B Salamon
Keyword(s):  
Spin Glass ◽  
Long Range ◽  
Range Order ◽  
Long Range Order
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