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Predicted electric field near small superconducting ellipsoids
We predict the existence of large electric fields near the surface of
superconducting bodies of ellipsoidal shape of dimensions comparable to the
penetration depth. The electric field is quadrupolar in nature with significant
corrections from higher order multipoles. Prolate (oblate) superconducting
ellipsoids are predicted to exhibit fields consistent with negative (positive)
quadrupole moments, reflecting the fundamental charge asymmetry of matter.Comment: To be published in Phys.Rev.Let
Superconductivity from Undressing
Photoemission experiments in high cuprates indicate that quasiparticles
are heavily 'dressed' in the normal state, particularly in the low doping
regime. Furthermore these experiments show that a gradual undressing occurs
both in the normal state as the system is doped and the carrier concentration
increases, as well as at fixed carrier concentration as the temperature is
lowered and the system becomes superconducting. A similar picture can be
inferred from optical experiments. It is argued that these experiments can be
simply understood with the single assumption that the quasiparticle dressing is
a function of the local carrier concentration. Microscopic Hamiltonians
describing this physics are discussed. The undressing process manifests itself
in both the one-particle and two-particle Green's functions, hence leads to
observable consequences in photoemission and optical experiments respectively.
An essential consequence of this phenomenology is that the microscopic
Hamiltonians describing it break electron-hole symmetry: these Hamiltonians
predict that superconductivity will only occur for carriers with hole-like
character, as proposed in the theory of hole superconductivity
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