Torque magnetometry on single-crystal high-temperature superconductors near the critical temperature: A scaling approach

Hofer, J.; Schneider, T.; Singer, J. M.; Willemin, M.; Keller, H.; Sasagawa, T.; Kishio, K.; Conder, K.; Karpiński, J.

doi:10.1103/physrevb.62.631

Cited by 50 publications

(111 citation statements)

References 31 publications

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“…where I conclude that the normal state diamagnetism observed in many cuprates [13,14,15,16,17,18] from KT and other "universal" critical exponents, but it is very close to the experimental Another strong argument in favor of 3D BEC in cuprates has been drawn using parameterfree fitting of experimental T c with BEC T c in more than 30 underdoped, optimally and overdoped samples [24]. Whereas the KT critical temperature expressed through the inplane penetration depth [12,25] k B T KT ≈ 0.9d 2 /(16πe 2 λ 2 H ) appears several times higher than the experimental values in many cases.…”

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confidence: 99%

“…A number of experiments (see, for example, [13,14,15,16,17,18] and references therein), including torque magnetometery, showed enhanced diamagnetism above T c . Originally it was explained as the conventional fluctuation diamagnetism in quasi-2D BCS superconductors (see, for example Ref.…”

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confidence: 99%

“…Originally it was explained as the conventional fluctuation diamagnetism in quasi-2D BCS superconductors (see, for example Ref. [16]). The data taken at relatively low magnetic fields (typically below Ref.…”

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confidence: 99%

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Normal-State Diamagnetism of Charged Bosons in Cuprate Superconductors

Alexandrov

2006

Phys. Rev. Lett.

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Normal state orbital diamagnetism of charged bosons quantitatively accounts for recent highresolution magnetometery results near and above the resistive critical temperature T c of superconducting cuprates. Our parameter-free descriptions of normal state diamagnetism, T c , upper critical fields and specific heat anomalies unambiguously support the 3D Bose-Einstein condensation of preformed real-space pairs with zero off-diagonal order parameter above T c at variance with phase fluctuation scenarios of cuprates.

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Normal-State Diamagnetism of Charged Bosons in Cuprate Superconductors

Alexandrov

2006

Phys. Rev. Lett.

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“…Although the crossover from the initial linear (m d = −χ d H) to nonlinear behavior is an expected feature of thermal fluctuations in homogeneous two (2D) and three (3D) dimensional superconductors, the occurrence of the minimum cannot be explained invoking these scenarios. [2][3][4][5][6][7] On the other hand, there is considerable evidence that cuprate and amorphous conventional superconductors are homogeneous over a limited spatial domain only. 8,[16][17][18][19][20][21][22] In this case, the growth of the correlation lengths is limited by approaching the transition temperature T c because it cannot exceed the respective extent of the homogenous domains.…”

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Diamagnetism, Nernst signal, and finite-size effects in superconductors above the transition temperatureTc

Schneider

2011

Phys. Rev. B

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Various superconductors, including cuprate superconductors, exhibit peculiar features above the transition temperature Tc. In particular the observation of a large diamagnetism and Nernst signal N in a wide temperature window above Tc attracted considerable attention. Noting that this temperature window exceeds the fluctuation dominated regime drastically and that in these materials the spatial extent of homogeneity is limited, we explore the relevance of the zero dimensional (0D)-model, neglecting thermal fluctuations. It is shown that both, the full 0D-model as well as its Gaussian approximation, mimic the essential features of the isothermal magnetization curves m d (H) in Pb nanoparticles and various cuprates remarkably well. This analysis also provides estimates for the spatial extent of the homogeneous domains giving rise to a smeared transition in zero magnetic field. The resulting estimates for the amplitude of the in-plane correlation length exhibit a doping dependence reflecting the flow to the quantum phase transition in the underdoped limit. Furthermore it is shown that the isothermal Nernst signal of a superconducting Nb0.15Si0.85 film, treated as N ∝ −m d , is fully consistent with this scenario. Accordingly, the observed diamagnetism above Tc in Pb nanoparticles, in the cuprates La1.91Sr0.09CuO4 and BiSr2Ca2CuO 8−δ , as well as the Nernst signal in Nb0.15Si0.85 films, are all in excellent agreement with the scaling properties emerging from the 0D-model, giving a universal perspective on the interplay between diamagnetism, Nernst signal, correlation length, and the limited spatial extent of homogeneity. Our analysis also provides evidence that singlet Cooper pairs subjected to orbital pair breaking in a 0D system are the main source of the observed diamagnetism and Nernst signal in an extended temperature window above Tc.

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“…For instance La 2 CuO 4 can be doped either by alkaline earth ions or oxygen to exhibit superconductivity. The empirical phase diagram of La 2-x Sr x CuO 4 [3][4][5][6][7][8][9][10][11], depicted in …”

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Universal properties of cuprate superconductors

Schneider

2003

Physica B: Condensed Matter

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To provide an understanding of the universal properties emerging from the empirical correlations and phase diagrams of cuprate superconductors , we invoke the scaling theory of finite temperature and quantum critical phenomena. The universal features are traced back to the existence of quantum critical lines, representing the end lines of the finite temperature transition surface. At the respective quantum critical lines two dimensional superconductor to insulator (2D-QSI) transitions and three dimensional superconductor to normal state (3D-QSN) transitions occur. The flow to this quantum critical points is tuned by doping, substitution and anisotropy. It is shown that the empirical correlations, like the dependence of T c on dopant and substitution concentration, the dependence of T c on zero temperature in-plane penetration depth, etc., reflect universal properties associated with the flow to these quantum critical points and of the crossover from one to the other. A detailed account of the flow to 2D-QSI and 3D-QSN criticality is a challenge for microscopic theories attempting to solve the puzzle of superconductivity in these materials. Key words: Cuprate superconductors, universal propertiesThe evidence for and the implications of critical fluctuations near the superconducting phase transition have been revisited quite often since the discovery of materials which exhibit high temperature superconductivity. Although it has been difficult to confront experiment with the zoo of microscopic theories and models, there have been notable successes in understanding the phenomenology of zero and finite temperature phase 1

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Torque magnetometry on single-crystal high-temperature superconductors near the critical temperature: A scaling approach

Cited by 50 publications

References 31 publications

Normal-State Diamagnetism of Charged Bosons in Cuprate Superconductors

Normal-State Diamagnetism of Charged Bosons in Cuprate Superconductors

Diamagnetism, Nernst signal, and finite-size effects in superconductors above the transition temperatureTc

Universal properties of cuprate superconductors

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