4 research outputs found
Theory of Extrinsic and Intrinsic Tunnelling in Cuprate Superconductors
A theory capable of explaining intrinsic and extrinsic tunnelling conductance
in underdoped cuprates has been devised that accounts for the existence of two
energy scales, their temperature and doping dependencies. The asymmetry and
inhomogeneity seen in extrinsic (normal metal - superconductor (NS)) tunnelling
and the normal-state gapped intrinsic (SS) conductance is explained, as well as
the superconducting gap and normal state pseudogap and the temperature
dependence of the full gap.Comment: 14 pages, 10 figures, misprints correcte
Order and quantum phase transitions in the cuprate superconductors
It is now widely accepted that the cuprate superconductors are characterized
by the same long-range order as that present in the Bardeen-Cooper-Schrieffer
(BCS) theory: that associated with the condensation of Cooper pairs. We argue
that many physical properties of the cuprates require interplay with additional
order parameters associated with a proximate Mott insulator. We review a
classification of Mott insulators in two dimensions, and contend that the
experimental evidence so far shows that the class appropriate to the cuprates
has collinear spin correlations, bond order, and confinement of neutral, spin
S=1/2 excitations. Proximity to second-order quantum phase transitions
associated with these orders, and with the pairing order of BCS, has led to
systematic predictions for many physical properties. We use this context to
review the results of recent neutron scattering, fluxoid detection, nuclear
magnetic resonance, and scanning tunnelling microscopy experiments.Comment: 20 pages, 13 figures, non-technical review article; some technical
details in the companion review cond-mat/0211027; (v3) added refs; (v4)
numerous improvements thanks to the referees, to appear in Reviews of Modern
Physics; (v6) final version as publishe