Role of stress in thin film alloy thermodynamics: competition between alloying and dislocation formation.
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.
Thayer
G E
GE
Sandia National Laboratories, Livermore, California 94551, USA.
Ozolins
V
V
Schmid
A K
AK
Bartelt
N C
NC
Asta
M
M
Hoyt
J J
JJ
Chiang
S
S
Hwang
R Q
RQ