title: Evidence for static magnetism in the vortex cores of ortho-II YBa2Cu3O6.50.
abstract: Evidence for static alternating magnetic fields in the vortex cores of underdoped YBa2Cu3O6+x is reported. Muon spin rotation measurements of the internal magnetic field distribution of the vortex state of YBa2Cu3O6.50 in applied fields of H = 1 T and H = 4 T reveal a feature in the high-field tail of the field distribution which is not present in optimally doped YBa2Cu3O6.95 and which fits well to a model with static magnetic fields in the vortex cores. The magnitude of the fields is estimated to be 18(2) G and decreases above T = 10 K. We discuss possible origins of the additional vortex core magnetism within the context of existing theories.
authors.affiliation: Department of Physics & Astronomy, University of British Columbia, Vancouver, Canada. miller@physics.ubc.ca
authors.forename: R I
authors.initials: RI
authors.lastname: Miller
authors.forename: R F
authors.initials: RF
authors.lastname: Kiefl
authors.forename: J H
authors.initials: JH
authors.lastname: Brewer
authors.forename: J E
authors.initials: JE
authors.lastname: Sonier
authors.forename: J
authors.initials: J
authors.lastname: Chakhalian
authors.forename: S
authors.initials: S
authors.lastname: Dunsiger
authors.forename: G D
authors.initials: GD
authors.lastname: Morris
authors.forename: A N
authors.initials: AN
authors.lastname: Price
authors.forename: D A
authors.initials: DA
authors.lastname: Bonn
authors.forename: W H
authors.initials: WH
authors.lastname: Hardy
authors.forename: R
authors.initials: R
authors.lastname: Liang