title: Percolative Superconductivity in Mg1-xB2.
abstract: Our results from various transport experiments on Mg1-xB2 indicate a surprising effect associated with the presence of a Mg deficiency in MgB2: the phase separation between Mg-vacancy rich and Mg-vacancy poor phases. The Mg-vacancy poor phase is superconducting, but the insulating nature of the Mg-vacancy rich phase probably originates from the Anderson (disorder-induced) localization of itinerant carriers. Furthermore, electron diffraction measurements indicate that within vacancy-rich regions these defects tend to order with intriguing patterns. This electronic phase separation in Mg1-xB2 shows similar, but also distinct characteristics compared with that observed in La(2)CuO(4+delta).
authors.affiliation: Department of Physics & Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA.
authors.forename: P A
authors.initials: PA
authors.lastname: Sharma
authors.forename: N
authors.initials: N
authors.lastname: Hur
authors.forename: Y
authors.initials: Y
authors.lastname: Horibe
authors.forename: C H
authors.initials: CH
authors.lastname: Chen
authors.forename: B G
authors.initials: BG
authors.lastname: Kim
authors.forename: S
authors.initials: S
authors.lastname: Guha
authors.forename: Marta Z
authors.initials: MZ
authors.lastname: Cieplak
authors.forename: S-W
authors.initials: SW
authors.lastname: Cheong