scholarly journals Fluctuation effects in underdoped cuprate superconductors under a magnetic field

2002 ◽  
Vol 66 (10) ◽  
Author(s):  
Ryusuke Ikeda
Keyword(s):  
Magnetic Field ◽  
Cuprate Superconductors ◽  
Fluctuation Effects

STABLE hc/e VORTICES IN SUPERCONDUCTORS WITH SPIN-CHARGE SEPARATION

1992 ◽  
Vol 06 (05n06) ◽  
pp. 509-526
Author(s):  
Subir Sachdev
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Normal State ◽  
Phenomenological Model ◽  
Charge Separation ◽  
Cuprate Superconductors ◽  
Superconducting Phase ◽  
Low Energy ◽  
Large N ◽  
Normal State Properties

A phenomenological model, F, of the superconducting phase of systems with spin-charge separation and antiferromagnetically induced pairing is studied. Above Hc1, magnetic flux can always pierce the superconductor in vortices with flux hc/2e, but regimes are found in which vortices with flux hc/e are preferred. Little-Park and other experiments, which examine periodicities with a varying magnetic field, always observe a period of hc/2e. The low energy properties of a symplectic large-N expansion of a model of the cuprate superconductors are argued to be well described by F. This analysis and some normal state properties of the cuprates suggest that hc/e vortices should be stable at the lowest dopings away from the insulating state at which superconductivity first occurs.

Fluctuation effects in the microwave conductivity of cuprate superconductors

1999 ◽  
Vol 59 (2) ◽  
pp. 1528-1537 ◽  
Author(s):  
J. R. Waldram ◽  
D. M. Broun ◽  
D. C. Morgan ◽  
R. Ormeno ◽  
A. Porch
Keyword(s):  
Cuprate Superconductors ◽  
Microwave Conductivity ◽  
Fluctuation Effects

scholarly journals MAGNETIC FIELD TUNING OF CHARGE AND SPIN ORDER IN THE CUPRATE SUPERCONDUCTORS

2002 ◽  
Vol 16 (20n22) ◽  
pp. 3156-3163 ◽  
Author(s):  
A. POLKOVNIKOV ◽  
S. SACHDEV ◽  
M. VOJTA ◽  
E. DEMLER
Keyword(s):  
Magnetic Field ◽  
Ground State ◽  
Charge Density Wave ◽  
Cuprate Superconductors ◽  
Density Wave ◽  
Spin Density Wave ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Spin Order ◽  
New Information

Recent neutron scattering, nuclear magnetic resonance, and scanning tunneling microscopy experiments have yielded valuable new information on the interplay between charge and spin density wave order and superconductivity in the cuprate superconductors, by using a perpendicular magnetic field to tune the ground state properties. We compare the results of these experiments with the predictions of a theory which assumed that the ordinary superconductor was proximate to a quantum transition to a superconductor with co-existing spin/charge density wave order.

Unusual magnetic-field dependence of the electrothermal conductivity in the mixed state of cuprate superconductors

1996 ◽  
Vol 53 (13) ◽  
pp. 8681-8686 ◽  
Author(s):  
J. A. Clayhold ◽  
Y. Y. Xue ◽  
C. W. Chu ◽  
J. N. Eckstein ◽  
I. Bozovic
Keyword(s):  
Magnetic Field ◽  
Field Dependence ◽  
Mixed State ◽  
Magnetic Field Dependence ◽  
Cuprate Superconductors

PREFORMED HOLE-PAIRS IN CUPRATE SUPERCONDUCTORS

2009 ◽  
Vol 23 (01) ◽  
pp. 53-76 ◽  
Author(s):  
R. J. SINGH
Keyword(s):  
Magnetic Field ◽  
Cuprate Superconductors ◽  
Charge Carriers ◽  
Nuclear Spins ◽  
Paramagnetic Resonance ◽  
Special Cases ◽  
Hyperfine Splittings ◽  
Single Formula ◽  
Electron Paramagnetic ◽  
Cu Ions

This paper consists of two parts: (1) mechanism of formation of hole-pairs and quantum stripes in cuprate superconductors, and (2) resistivity versus temperature variation in YBa 2 Cu 3 O 7-δ superconductor with different doping levels in the range 400–Tc. (1) On deoxygenation, CuO 2 plane of high-temperature cuprate superconductors are broken into small magnetically isolated fragments, predominantly Cu -tetramer (CuO) 4. Its electron paramagnetic resonance spectra show fine and hyperfine splittings. It was concluded that these splittings are due to FM coupling of the electronic spins of the four holes on the four Cu -ions in (CuO) 4 as well as the FM coupling of the nuclear spins of the four Cu -ions. A magnetic field is generated perpendicular to CuO 2 plane due to the spin magnetic moment of four holes and their orbiting around the (CuO) 4 frame. In the nondeoxygenated superconductors, this magnetic field leads to the formation of quantum stripes of free charge carriers and in special cases to the formation of preformed hole-pairs. This is the first model of a hole-pair, though its existence has been conjectured from various experimental results. (2) The electrical conduction in superconductors along c-axis seems to arise from the movement of free holes and along a-axis from the parallel combination of resistivities arising from the movement of free holes and paired holes, but no single formula connecting ρ and T is applicable to explain resistivities either along c- or a-axis in the entire temperature range. Nature of charge carriers seems to change continuously as the temperature is lowered. In the range 200–Tc, both along the c- and a-axes, the experimental resistivities depart significantly from those calculated by the formula applicable in the range 400–200 K. Plausible explanation has been suggested for the departure of experimental resistivities from the calculated ones in the low temperature region.

scholarly journals MAGNETIC FIELD EFFECTS On Tc AND THE PSEUDOGAP ONSET TEMPERATURE IN CUPRATE SUPERCONDUCTORS

2002 ◽  
Vol 16 (20n22) ◽  
pp. 3176-3179
Author(s):  
QIJIN CHEN ◽  
YING-JER KAO ◽  
ANDREW P. IYENGAR ◽  
K. LEVIN
Keyword(s):  
Magnetic Field ◽  
Coherence Length ◽  
Cuprate Superconductors ◽  
Onset Temperature ◽  
Magnetic Field Effects ◽  
Arbitrary Coupling ◽  
Field Effects

We study the sensitivity of Tc and the pseudogap onset temperature, T*, to low fields, H, for cuprate superconductors, using a BCS-based approach extended to arbitrary coupling. We find that T* and Tc, which are of the same superconducting origin, have very different H dependences. The small coherence length makes T* rather insensitive to the field. However, the presence of the pseudogap at Tc makes Tc more sensitive to H. Our results for the coherence length ξ fit well with existing experiments. We predict that very near the insulator ξ will rapidly increase.

Vortex Structure: Lattice, Glass, or Liquid?

1989 ◽  
Vol 169 ◽  
Author(s):  
Robert J. Soulen ◽  
Stuart A. Wolf
Keyword(s):  
Magnetic Field ◽  
Phase Diagram ◽  
Vortex Structure ◽  
Cuprate Superconductors ◽  
Magnetic Phase ◽  
Magnetic Phase Diagram ◽  
Type Ii ◽  
Type Ii Superconductors

AbstractRecent measurements of the dissipation in cuprate superconductors in a magnetic field have been interpreted as providing evidence for the presence of new phases in type II superconductors: flux liquids or flux glasses. We suggest that a more conventional interpretation in terms of the electrodynamics of vortices can adequately account for all the observations. Based on this model, we propose a magnetic phase diagram.

OPTICAL PROPERTIES OF CUPRATE SUPERCONDUCTORS INFLUENCED BY A MAGNETIC FIELD

1991 ◽  
Vol 05 (10) ◽  
pp. 1539-1549 ◽  
Author(s):  
H. J. WEBER
Keyword(s):  
Magnetic Field ◽  
Circular Dichroism ◽  
External Magnetic Field ◽  
Time Reversal ◽  
Cuprate Superconductors ◽  
Magnetic Circular Dichroism ◽  
Magnetic Field Effects ◽  
Transmission Measurements ◽  
Circular Dichroïsm ◽  
The Magnetic Field

Reflection measurements on a one-domain single crystal of YBa 2 Cu 3 O 7-δ and transmission measurements on single crystals of Bi 2 Sr 2 CaCu 2 O 8 show a state of spontaneously broken symmetry below certain transition temperatures T s somewhat above the respective superconduction temperature T c . In both materials the sign of the effect can be controlled by an external magnetic field. In transmission measurements on films of YBa 2 Cu 3 O 7-δ near T s a remanent circular dichroism is observed after applying an external magnetic field. Furthermore, the films show a Curie-Weiss type increase of magnetic circular dichroism near T s . The magnetic field effects are considered as evidence for a state with broken time reversal symmetry below T s .

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