title: Role of stress in thin film alloy thermodynamics: competition between alloying and dislocation formation.
abstract: Using scanning tunneling microscopy (STM) and first-principles local-spin-density-approximation calculations to study submonolayer films of Co (1-c)Ag (c)/Ru(0001) alloys, we have discovered a novel phase-separation mechanism. When the Ag concentration c exceeds 0.4, the surface phase separates between a dislocated, pure Ag phase and a pseudomorphically strained Co(0.6)Ag (0.4) surface alloy. We attribute the phase separation to the competition between two stress relief mechanisms: surface alloying and dislocation formation. The agreement between STM measurements and our calculated phase diagram supports this interpretation.
authors.affiliation: Sandia National Laboratories, Livermore, California 94551, USA.
authors.forename: G E
authors.initials: GE
authors.lastname: Thayer
authors.forename: V
authors.initials: V
authors.lastname: Ozolins
authors.forename: A K
authors.initials: AK
authors.lastname: Schmid
authors.forename: N C
authors.initials: NC
authors.lastname: Bartelt
authors.forename: M
authors.initials: M
authors.lastname: Asta
authors.forename: J J
authors.initials: JJ
authors.lastname: Hoyt
authors.forename: S
authors.initials: S
authors.lastname: Chiang
authors.forename: R Q
authors.initials: RQ
authors.lastname: Hwang