High-temperature superconductivity: the explanation

Alexandrov, A. S.

doi:10.1088/0031-8949/83/03/038301

Cited by 31 publications

(27 citation statements)

References 97 publications

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“…Beyond the BKT vortex and TDGL scenario, other phase-locking scenarios, such as Bose-Einstein condensation of bipolarons [2,3,61] and phase-coherence percolation [4,5] may also be consistent with the observed behaviour. In both of these cases pairing and phase coherence are also distinct processes.…”

Section: Discussionsupporting

confidence: 61%

Separating pairing from quantum phase coherence dynamics above the superconducting transition by femtosecond spectroscopy

Madan

Kurosawa

Toda

et al. 2014

Sci Rep

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In classical superconductors an energy gap and phase coherence appear simultaneously with pairing at the transition to the superconducting state. In high-temperature superconductors, the possibility that pairing and phase coherence are distinct and independent processes has led to intense experimental search of their separate manifestations. Using femtosecond spectroscopy methods we now show that it is possible to clearly separate fluctuation dynamics of the superconducting pairing amplitude from the phase relaxation above the critical transition temperature. Empirically establishing a close correspondence between the superfluid density measured by THz spectroscopy and superconducting optical pump-probe response over a wide region of temperature, we find that in differently doped Bi2Sr2CaCu2O8+δ crystals the pairing gap amplitude monotonically extends well beyond Tc, while the phase coherence shows a pronounced power-law divergence as T → Tc, thus showing that phase coherence and gap formation are distinct processes which occur on different timescales.

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Section: Discussionsupporting

confidence: 61%

Separating pairing from quantum phase coherence dynamics above the superconducting transition by femtosecond spectroscopy

Madan

Kurosawa

Toda

et al. 2014

Sci Rep

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“…Alkene coated cells may greatly enhance the lifetime of quantum memory applications [6] or the storage time of light in "slow-light" experiments [28,29]. In the context of geophysical measurements, extremely narrow lines can reduce orientation dependent "heading errors" due to the non-linear Zeeman effect, a significant issue in geomagnetic surveying [27]. While spin-exchange relaxation is difficult to completely eliminate at high field, the use of only a single isotope and hyperfine pumping may reduce such relaxation considerably.…”

mentioning

confidence: 99%

Polarized Alkali-Metal Vapor with Minute-Long Transverse Spin-Relaxation Time

et al. 2010

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We demonstrate lifetimes of atomic populations and coherences in excess of 60 seconds in alkali vapor cells with inner walls coated with an alkene material. This represents two orders of magnitude improvement over the best paraffin coatings. Such anti-relaxation properties will likely lead to substantial improvements in atomic clocks, magnetometers, quantum memory, and enable sensitive studies of collisional effects and precision measurements of fundamental symmetries. [7,8], and precision measurements of fundamental symmetries [9]. One method for achieving long coherence times is to coat the walls of a cell with an anti-relaxation film such as paraffin [10,11] or octadecyltrichlorosilane [12]. Conventional paraffin coatings are formed from long-chain alkane molecules, supporting approximately 10 4 atom-wall collisions before depolarizing the alkali spins. In this Letter we report on the remarkable anti-relaxation properties of a new, alkene based, coating. With proper experimental arrangements, we realize coherence lifetimes on the order of 1 minute in a 3 cm diameter cell, corresponding to about 10 6 polarization preserving bounces. To the best of our knowledge, this corresponds to the narrowest electron paramagnetic resonance ever observed.One of the key ingredients to realizing such long lifetimes is to work in magnetic fields such that the Larmor precession frequency is small compared to the spinexchange rate, and to optically pump the alkali vapor with circularly polarized light. This largely eliminates relaxation due to spin-exchange collisions, the so called spin-exchange relaxation-free (SERF) regime [13,14]. SERF magnetometers presently hold the record for magnetic field sensitivity of any device [15,16], but usually require operation at temperatures in excess of 150• C. The alkene coating described here enables operation of such a magnetometer in a room temperature environment, dramatically expanding its useful range of application, especially where low power consumption is important. We present an experimental and theoretical investigation of a room temperature atomic magnetometer operating in the SERF regime. Experiment and theory are in good agreement with each other.Exchange of atoms between the bulb of the cell and the stem with the Rb reservoir (Fig.

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“…The disproportionation scenario implies the composite local boson to be anyhow an integral part of a stable many-electron atomic configuration, 3d n+1 or 3d n−1 . Microscopic nature of the "attractive force which could overcome the natural Coulomb repulsion between two electrons which constitute a Bose pair" [41] evolves both from main intra-atomic correlations and electron-lattice polarisation effects [22] providing the stability of 3d n±1 configurations.…”

Section: Local Composite Bosons In 3d N Systemsmentioning

confidence: 99%

Perspectives of disproportionation driven superconductivity in strongly correlated 3d compounds

Moskvin¹

2013

J. Phys.: Condens. Matter

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Abstract. Disproportionation in 3d compounds can give rise to an unconventional electron-hole Bose liquid with a very rich phase diagram from a Bose metal, charge ordering insulator to an inhomogeneous Bose superfluid. Optimal conditions for the disproportionation driven high-T c superconductivity are shown to realize only for several Jahn-Teller d n configurations that permit the formation of well defined local composite bosons. These are the high-spin d 4 , low-spin d 7 , and d 9 configurations given the octahedral crystal field, and the d 1 , high-spin d 6 configurations given the tetrahedral crystal field. The disproportionation reaction has a peculiar "anti-JahnTeller" character lifting the bare orbital degeneracy. Superconductivity in the d 4 and d 6 systems at variance with d 1 , d 7 , and d 9 systems implies an unavoidable coexistence of the spin-triplet composite bosons and a magnetic lattice. We argue that unconventional high-T c superconductivity observed in quasi-2D cuprates with tetragonally distorted CuO 6 octahedra and iron-based layered pnictides/chalcogenides with tetrahedrally coordinated Fe 2+ ions can be a key argument supporting the disproportionation scenario is at work in these compounds.

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High-temperature superconductivity: the explanation

Cited by 31 publications

References 97 publications

Separating pairing from quantum phase coherence dynamics above the superconducting transition by femtosecond spectroscopy

Separating pairing from quantum phase coherence dynamics above the superconducting transition by femtosecond spectroscopy

Polarized Alkali-Metal Vapor with Minute-Long Transverse Spin-Relaxation Time

Perspectives of disproportionation driven superconductivity in strongly correlated 3d compounds

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