First Observation for a Cuprate Superconductor of Fluctuation-Induced Diamagnetism Well Inside the Finite-Magnetic-Field Regime

Carballeira, C.; Mosqueira, J.; Revcolevschi, A.; Vidal, F.

doi:10.1103/physrevlett.84.3157

Cited by 57 publications

(68 citation statements)

References 22 publications

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“…This compound is stoichiometric, which minimizes the randomness of dopant atom distribution and then the corresponding disorder and inhomogeneities. 1 These data will be then used to check if the existing GL approaches with fluctuations of vortices and of Cooper pairs 3,7,8,9,23,24,25 explain, at quantitatively and consistently above and below T C , the diamagnetism measured in homogeneous cuprate superconductors.…”

Section: 22mentioning

confidence: 99%

Diamagnetism around the Meissner transition in a homogeneous cuprate single crystal

2007

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The in-plane diamagnetism around the Meissner transition was measured in a Tl2Ba2Ca2Cu3O10 single crystal of high chemical and structural quality, which minimizes the inhomogeneity and disorder rounding effects on the magnetization. When analyzed quantitatively and consistently above and below the transition in terms of the Ginzburg-Landau (GL) approach with fluctuations of Cooper pairs and vortices, these data provide a further confirmation that the observed Meissner transition is a conventional GL superconducting transition in a homogeneous layered superconductor.

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Section: 22mentioning

confidence: 99%

Diamagnetism around the Meissner transition in a homogeneous cuprate single crystal

2007

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“…This diamagnetism should be non-Gaussian and survive to 33 T and beyond, if it is to be related at all to e N . However, in prior reports of "fluctuation diamagnetism" in cuprates [74,75] found features that were anomalous and difficult to understand, but one report claimed [76] a good fit to conventional Gaussian theory. Naughton then drew our attention to his report [73] of an unexplained diamagnetic signal in Hg 2212 that persists to 33 T and 200 K.…”

Section: Enhanced Diamagnetism Above Tcmentioning

confidence: 99%

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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“…As we have shown above, however, the Sommerfeld cancellation is totally broken in HTSC's due to the current VC's. In the under-doped HTSC's, the diamagnetism due to the fluctuation of the SC order parameter above T c , which is represented theoretically by the Azlamazov-Larkin term and is known to sensitive to the strength of the field, is observed only in the vicinity of T c ; T < ∼ T c +5K [37,55]. In conclusion, the abrupt increment of ν below T * ( > ∼ 100K) should be the quasiparticle origin, as discussed in Ref.…”

Section: Af Fluctuationsmentioning

confidence: 99%

From Kondo Effect to Fermi Liquid

Kontani

Yamada

2005

J. Phys. Soc. Jpn.

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The Kondo effect has been playing an important role in strongly correlated electon systems. The important point is that the magnetic impurity in metals is a typical example of the Fermi liquid. In the system the local spin is conserved in the ground state and continuity with respect to Coulomb repulsion U is satisfied. This nature is satisfied also in the periodic systems as far as the systems remain as the Fermi liquid. This property of the Fermi liquid is essential to understand the cuprate high-Tc superconductors (HTSC). On the basis of the Fermi liquid theory we develop the transport theory such as the resistivity and the Hall coefficient in strongly correlated electron systems, such as HTSC, organic metals and heavy Fermion systems. The significant role of the vertex corrections for total charge-and heat-currents on the transport phenomena is explained. By taking the effect of the current vertex corrections into account, various typical non-Fermi-liquid-like transport phenomena in systems with strong magnetic and/or superconducting flucutations are explained within the Fermi liquid theory. 1.IntroductionSince the discovery of Kondo Effect, the theory of electron correlation has been developed remarkably. In particular, the study of the strongly correlated electron systems such as cuprates and heavy fermions is actively performed. In this article we discuss the contribution of Kondo theory to the theory of strongly correlated electron systems. The key word is the singlet: The ground state of the single impurity in metals is the singlet where a localized spin is coupled antiferromagnetically with conduction electron spin. The resonating-valence-bond (RVB) state is a spin singlet state and is considered to be the basis of the cuprate high-T c superconductivity (HTSC). By using Anderson's orthogonality theorem, we show that the Fermi liquid state is nothing but the RVB state in metal. As a result, we can reasonably arrive at the pairing theory of superconductivity. Anderson HamiltonianIn 1961 Anderson presented the following Hamiltonian and explained the appearance of a localized moment in metals by using the Hartree-Fock approximation.[1]The first term is the energy of conduction electrons and the third term is the d-electron part. The last term is the Coulomb repulsion between two d-electrons and is the only many-body interaction. The symmetric Anderson Hamiltonian possesses the electron-hole symmetry and is easy to understand the physical meaning because of the suppressed charge fluctuations. By assuming the average number of d-electrons is unity and taking the nonmagnetic case (< n dσ >=< n d−σ >= 1/2) ,where E Here ρ is the density of states of conduction electrons at the Fermi energy. Hereafter, we assume the band-width of conduction band is infinite and ρ is constant. 2-1. Kondo effectAnderson explained the existence of magnetic moment as the effect of electron correlation. However, there existed a long standing mystery for these 30 years.[2] As shown in Fig.1, when we decrease the temperature, the resid...

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First Observation for a Cuprate Superconductor of Fluctuation-Induced Diamagnetism Well Inside the Finite-Magnetic-Field Regime

Cited by 57 publications

References 22 publications

Diamagnetism around the Meissner transition in a homogeneous cuprate single crystal

Diamagnetism around the Meissner transition in a homogeneous cuprate single crystal

Nernst effect in high-Tcsuperconductors

From Kondo Effect to Fermi Liquid

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