title: Limits on spin-charge separation from h/2e fluxoids in very underdoped YBa2Cu3O(6+x).
abstract: Magnetic flux in superconductors is usually quantized in units of h/2e. Here we report scanning SQUID and scanning Hall probe studies of single fluxoids in high purity YBa2Cu3O6.35 crystals (T(c) less, similar 13 K), extending flux quantization studies to a region of the cuprate phase diagram where the superfluid density is sufficiently low that novel behavior has been predicted. Some scenarios in which superconductivity results from spin-charge separation predict h/e fluxoids in materials with low superfluid density. Our observations of only h/2e fluxoids set limits on these theories.
authors.affiliation: Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA.
authors.forename: J C
authors.initials: JC
authors.lastname: Wynn
authors.forename: D A
authors.initials: DA
authors.lastname: Bonn
authors.forename: B W
authors.initials: BW
authors.lastname: Gardner
authors.forename: Y J
authors.initials: YJ
authors.lastname: Lin
authors.forename: R
authors.initials: R
authors.lastname: Liang
authors.forename: W N
authors.initials: WN
authors.lastname: Hardy
authors.forename: J R
authors.initials: JR
authors.lastname: Kirtley
authors.forename: K A
authors.initials: KA
authors.lastname: Moler