Nernst effect in superconducting Y-Ba-Cu-O

Zeh, M.; Ri, H.-C.; Kober, F.; Huebener, R. P.; Ustinov, A. V.; Mannhart, J.; Gross, Rudolf; Gupta, Arunava

doi:10.1103/physrevlett.64.3195

Cited by 104 publications

(32 citation statements)

References 12 publications

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“…The early results on OP cuprates in the "fluctuation" regime [53,56] were deemed compatible with the prevailing expectation that, although flucutations are strongly enhanced in cuprates [57], the data appeared to be adequately described by conventional Gaussian fluctuation theory [58,59].…”

Section: Optimally-doped Cupratessupporting

confidence: 67%

“…1). However, the existence of unusually large "fluctuation signals" extending 10-20 K above T c was noted in OP Bi 2212 and YBCO [53,56].…”

Section: Optimally-doped Cupratesmentioning

confidence: 99%

“…In the cuprates, early Nernst [53,54,55] and Ettingshausen [56] experiments were restricted to OP, bilayer cuprates. The results were largely confined to the vortexliquid state below T c , and analyzed to extract vortex parameters such as s φ (Eq.…”

Section: Optimally-doped Cupratesmentioning

confidence: 99%

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Nernst effect in high-Tcsuperconductors

2006

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The observation of a large Nernst signal eN in an extended region above the critical temperature Tc in hole-doped cuprates provides evidence that vortex excitations survive above Tc. The results support the scenario that superfluidity vanishes because long-range phase coherence is destroyed by thermally-created vortices (in zero field), and that the pair condensate extends high into the pseudogap state in the underdoped (UD) regime. We present a series of measurements to high fields H which provide strong evidence for this phase-disordering scenario. Measurements of eN in fields H up to 45 T reveal that the vortex Nernst signal has a characteristic "tilted-hill" profile, which is qualitatively distinct from that of quasi-particles. The hill profile, which is observed above and below Tc, underscores the continuity between the vortex-liquid state below Tc and the Nernst region above Tc. The upper critical field (depairing field) Hc2 determined by the hill profile (in slightly UD to overdoped samples) displays an anomalously weak T dependence, which is consistent with the phase-disordering scenario. We contrast the Nernst results and Hc2 behavior in hole-doped and electron-doped cuprates. Contour plots of eN (T, H) in the T -H plane clearly bring out the continuous extension of the low-T vortex liquid state into the the high-T Nernst region in holedoped cuprates (but not in the electron-doped cuprate). The existence of an enhanced diamagnetic magnetization M that survives to intense H above Tc is obtained from torque magnetometry. The observed M scales accurately like eN above Tc, confirming that the large Nernst signal is associated with local diamagnetic supercurrents that persist above Tc. We emphasize implications of the new features in the phase diagram implied by the high-field results, and discuss several theories.

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Section: Optimally-doped Cupratessupporting

confidence: 67%

“…1). However, the existence of unusually large "fluctuation signals" extending 10-20 K above T c was noted in OP Bi 2212 and YBCO [53,56].…”

Section: Optimally-doped Cupratesmentioning

confidence: 99%

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Nernst effect in high-Tcsuperconductors

2006

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“…From investigation of the Nernst effect in polycrystalline Tl2Ba2CaCu2Ox films using pulsed laser heating to induce temperature gradients in the film [ 1 ], activation energies for depinning of flux tubes have been derived assuming thermally activated flux motion. A Nernst effect was also observed in epitaxial Y-Ba-Cu-O films [2 ] by continuous heating [4]. From measurement of the Nernst field and the film resistivity due to flux motion, the transport entropy of flux tubes near Tc has been estimated.…”

mentioning

confidence: 93%

“…The theory for VT< VT~,~t is applied to an analysis of experimental results obtained for polycrystalline Tl2Ba2CaCu2Ox films. From the temperature dependence of the Nernst field we derive activation energies for flux depinning.Thermomagnetic effects in high-To superconductors have recently been observed by several groups [1][2][3]. From investigation of the Nernst effect in polycrystalline Tl2Ba2CaCu2Ox films using pulsed laser heating to induce temperature gradients in the film [ 1 ], activation energies for depinning of flux tubes have been derived assuming thermally activated flux motion.…”

mentioning

confidence: 99%

Nernst effect in high-Tc superconductors

Lengfellner¹,

Schnellbögl²

1991

Physica C: Superconductivity

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In this paper we present a description of the Nernst electric field E generated by forced flux tube motion due to a temperature gradient VT. Depending on the value of VTwith respect to a critical gradient VTmt, we find for VT/VTc,lt << 1 a regime Eoc VT, in close analogy to the regime of thermally activated flux flow in transport current measurements (characterized by an electric field proportional to the transpoxt current). The theory for VT< VT~,~t is applied to an analysis of experimental results obtained for polycrystalline Tl2Ba2CaCu2Ox films. From the temperature dependence of the Nernst field we derive activation energies for flux depinning.Thermomagnetic effects in high-To superconductors have recently been observed by several groups [1][2][3]. From investigation of the Nernst effect in polycrystalline Tl2Ba2CaCu2Ox films using pulsed laser heating to induce temperature gradients in the film [ 1 ], activation energies for depinning of flux tubes have been derived assuming thermally activated flux motion. A Nernst effect was also observed in epitaxial Y-Ba-Cu-O films [2 ] by continuous heating [4]. From measurement of the Nernst field and the film resistivity due to flux motion, the transport entropy of flux tubes near Tc has been estimated. The transport entropy has also been investigated in a YBa2Cu307 single crystal, using the Ettingshausen effect [ 3 ]; from measurements of the entropy flow the transport line energy of a vortex has been determined. In this paper, we develop a theory to describe flux motion due to a temperature gradient and derive an expression for the Nernst electric field. We then use the theory for an analysis of experimental data reported in ref. [ 1 ].The °u°,.,,.;,. field ,,,,,,,.o,,a by nux m'~tio n i~ givon by E= ( 1/c)B×v [5], where B is the magnetic field in the material and v the velocity of B with respect to the material. For flux hopping transverse to B, with hopping rate v and hopping length l, E= (1/c)Bvl.For a derivation of E we follow a theory given by Brandt [ 6 ] for the case that the driving force on flux tubes is the Lorentz force due to a transport current.Instead of the Lorentz force we regard the thermal force Fth= -VT SL [ 7] that is due to a temperature gradient VT and a transport entropy SL of a flux tube, where S is the transport entropy per unit length and L is the flux tube length. For the net jump rate which is the difference of jump rates along and against the driving force we find then. using Andersons model of thermal activated hopping [ 8 ], _voexp [-(kTa~-kY~-'Sm/)] , (I) where kTa is an activation energy and Vo an attempt frequency~ At a critical temperature gradient VTcrit = kga/(SLI) the pinning energy and the work done by the thermal force over the hopping length I are equal. With this expression we findFor a small argument of sinh, i.e. VT/VTcrtt << 1, this expression can be simplified to E-2Blv° Ta VT ( ~) TVT¢r, ------~tOur treatment shows therefore that for small driving 0921-4534/91/$03.50 © 1991 -Elsevier Science Publishers B.V. ( North...

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Peltier‐effect in the mixed state of (Bi, Pb)₂Sr₂Ca₂Cu₃O_δ

1994

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We present measurements of the Peltier-effect in the mixed state of Bi,.,,Pb,,SrzCazCu,Od. The Peltier-coefficient broadens in a magnetic field quite similar to the resistivity and the thermopower. Comparison with the thermopower shows that Onsagers relation holds well. The occurrence of the Peltier-heat in the mixed state well below T, implies that the electric current is accompanied by a large heat current. We show that the vortex contribution to the Peltier-heat is negligibly small. Therefore the heat current has to be attributed to normal quasiparticle excitations. Our results indicate that this quasiparticle contribution to the heat current remains large even at temperatures far below c.

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Nernst effect in superconducting Y-Ba-Cu-O

Cited by 104 publications

References 12 publications

Nernst effect in high-Tcsuperconductors

Nernst effect in high-Tcsuperconductors

Nernst effect in high-Tc superconductors

Peltier‐effect in the mixed state of (Bi, Pb)₂Sr₂Ca₂Cu₃O_δ

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Nernst effect in superconducting Y-Ba-Cu-O

Cited by 104 publications

References 12 publications

Nernst effect in high-Tcsuperconductors

Nernst effect in high-Tcsuperconductors

Nernst effect in high-Tc superconductors

Peltier‐effect in the mixed state of (Bi, Pb)2Sr2Ca2Cu3Oδ

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Peltier‐effect in the mixed state of (Bi, Pb)₂Sr₂Ca₂Cu₃O_δ