Measurement of the London moment in two high-temperature superconductors

Verheijen, A. A.; Ruitenbeek, J. M. van; Ouboter, R. de Bruyn; Jongh, L.J. de

doi:10.1038/345418a0

Cited by 44 publications

(36 citation statements)

References 7 publications

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“…This law is experimentally confirmed (see e.g. [8] and references therein). Of crucial significance is the fact that the experimentally observed London Law involves only the exact values of the fundamental constants, and not on materials properties specific to the superconductor (such as an effective mass for electrons).…”

supporting

confidence: 58%

Violation of the London law and Onsager–Feynman quantization in multicomponent superconductors

Babaev

Ashcroft

2007

Nature Phys

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Two quite fundamental principles governing the response to rotation of single-component superfluids and superconductors, the London law [1] relating the angular velocity to a subsequently established magnetic field, and the OnsagerFeynman quantization of superfluid velocity [2,3] are shown to be violated in a two-component superconductor. The manifestation of the two principles normally involves the fundamental constants alone, but this no longer holds as is demonstrated explicitly for the projected liquid metallic states of hydrogen and deuterium at high pressures. The rotational responses of liquid metallic hydrogen or deuterium identify them as a new class of dissipationless states; they also directly point to a particular experimental route for verification of their existence.Non-classical response to rotation is a hallmark of quantum ordered states such as superconductors and superfluids. The rotational responses of all presently known single-component "super" states of matter (superconductors, superfluids and supersolids) are largely described by two fundamental principles and fall into two categories according to whether the systems are composed of neutral or charged particles. For superfluid systems composed of electrically neutral particles (liquids, vapors, or even solids [4]) and for slow rotations, a fraction of the system, the superfluid fraction, remains irrotational. However in response to rotation exceeding a certain critical rotation frequency, the superfluid fraction comes into rotation by means of vortex formation. Onsager and Feynman [2,3] pointed out that the superfluid velocity (v) in these vortices in single-component systems is quantized and the circulation quantum K depends only on particle's mass m and Planck's constant h: K = (1/2π) v · dl =h/m. Here we mention that for superfluids with e.g. p-wave symmetry of the order parameter which are also invariant under simultaneous phase and spin transformations this quantization is modified [5]. We also mention that a special situation occur in a multicomponent superfluid with a dissipationless drag (Andreev-Bashkin effect) where a superfluid velocity of one condensate can carry superfluid density of another [6,7]. Below however we will consider the mixture of charged condensates only with the simplest symmetry of the order parameter coupled by a gauge field.For systems composed of charged particles and which are also superconducting (electronic Cooper pairs in metals, or protonic Cooper pairs in neutron stars) vortices are not induced by rotation; however, the rotational response of these systems is no less interesting. London showed that a uniformly rotating single component superconductor generates a persistent current in a thin layer near its surface, and this in turn produces a detectable magnetic field, the London field [1]. London related this field to the rotation frequency, Ω, according to B = −(2mc/e)Ω, where m is the electron's mass, e denotes it electric charge and c is the speed of light. This law is experimentally confirmed (see ...

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supporting

confidence: 58%

Violation of the London law and Onsager–Feynman quantization in multicomponent superconductors

Babaev

Ashcroft

2007

Nature Phys

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“…Current experimental observations are consistent with the universal character of London's Law (see, e.g., [4,5]). London effect also contributes to the magnetic field of pulsars, which are rotating protonic superconductors.…”

supporting

confidence: 78%

“…To simplify notation we employ the units = c = 1, in which q and γ are the absolute value of bare electric charge and bare inverse mass of two electrons. According to London [2], the superconductor, rotating with the angular velocity Ω, generates the magnetic fieldCurrent experimental observations are consistent with the universal character of London's Law (see, e.g., [4,5]). London effect also contributes to the magnetic field of pulsars, which are rotating protonic superconductors.…”

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confidence: 93%

Rotational response of superconductors: Magnetorotational isomorphism and rotation-induced vortex lattice

Babaev

Svistunov

2014

Phys. Rev. B

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The analysis of nonclassical rotational response of superfluids and superconductors was performed by Onsager (in 1949) [1] and London (in 1950) [2] and crucially advanced by Feynman (in 1955) [3]. It was established that, in thermodynamic limit, neutral superfluids rotate by forming-without any threshold-a vortex lattice. In contrast, the rotation of superconductors at angular frequency Ω-supported by uniform magnetic field BL ∝ Ω due to surface currents-is of the rigid-body type (London Law). Here we show that, neglecting the centrifugal effects, the behavior of a rotating superconductor is identical to that of a superconductor placed in a uniform fictitious external magnetic filedH = −BL. In particular, the isomorphism immediately implies the existence of two critical rotational frequencies in type-2 superconductors.Superconductors and superfluids are distinguished by their Non-Classical Rotational Response (NCRR), strikingly different from the rotational response of ordinary states of matter. The NCRRs have a high degree of universality rooted in the fact that superconductors and superfluid break U(1) symmetry and, at long-length scales, are described by a complex scalar field theory. Rotating superfluids form vortex lattices [1,3], which is routinely used to demonstrate superfluid properties.By contrast, a rotational response of a superconductor-known as the London Law [2]-is different. It is derived from the minimal, constantdensity (n = const) model of superconductivitywhere F is the free energy density, φ is the superconducting phase, A is the vector potential, m and e are the fundamental constants: the mass and charge of the electron. To simplify notation we employ the units = c = 1, in which q and γ are the absolute value of bare electric charge and bare inverse mass of two electrons. According to London [2], the superconductor, rotating with the angular velocity Ω, generates the magnetic fieldCurrent experimental observations are consistent with the universal character of London's Law (see, e.g., [4,5]). London effect also contributes to the magnetic field of pulsars, which are rotating protonic superconductors. Below we show that the state of a rapidly rotating type-2 superconductor becomes different from the London one. The general solution to the problem is readily obtained by observing that there is an isomorphism between rotating superconductor and a non-rotating superconductor in a uniform external magnetic field.Assuming electroneutrality as a natural physical condition and confining ourselves, for simplicity, with the constant-density regime, we put superconducting matter field onto a uniformly rotating uniformly charged background. (In superconducting metals, the background charge is associated with the crystal lattice of positively charged ions. In the case of protonic superconductivity in a neutron star, the background charge comes from normal electrons.) In a neutral superfluid, rotation is equivalent to introduction of a fictitious vector potential (and also the centrifugal potential, whi...

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“…The London moment is a universal magnetomechanical property of rotating superconductors, independent of specific material properties, and verified not only in conventional superconductors, but also in the high-T c 11 and heavy fermion species. 12 It furnishes a generalization of the familiar phenomenon of Meissner screening to noninertial, material reference frames of the superconducting state.…”

Section: Introductionmentioning

confidence: 99%

Electromagnetomotive force fields in noninertial reference frames and accelerated superconducting quantum interferometers

et al. 2001

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We discuss the prospects of detecting with high precision the force fields related to noninertiality in superconducting circuits. Special emphasis is laid on the perfectly conducting and perfect diamagnetism analogues of the Tolman-Stewart and Barnett effects, respectively. The influence of acceleration and rotation on the electrodynamics of superconducting interferometers is explicitly described. In particular, we show how motion induced changes of the oscillation frequency of the local Josephson oscillators in superconducting quantum interference filters can be used for precision measurements of acceleration in free space.

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Measurement of the London moment in two high-temperature superconductors

Cited by 44 publications

References 7 publications

Violation of the London law and Onsager–Feynman quantization in multicomponent superconductors

Violation of the London law and Onsager–Feynman quantization in multicomponent superconductors

Rotational response of superconductors: Magnetorotational isomorphism and rotation-induced vortex lattice

Electromagnetomotive force fields in noninertial reference frames and accelerated superconducting quantum interferometers

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