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Atomic Scale Understanding of Intermixing Behavior of Thin Metal Multlayer. Sang-Pil Kim, Jae-Young Park * , Seung-Cheol Lee, Yong-Jae Chung § , Chung-Nam Whang * and Kwang-Ryeol Lee Korea Institute of Science and Technology, Seoul, Korea § Hanyang University, Seoul, Korea
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Atomic Scale Understanding of Intermixing Behavior of Thin Metal Multlayer Sang-Pil Kim, Jae-Young Park*, Seung-Cheol Lee, Yong-Jae Chung§, Chung-Nam Whang* and Kwang-Ryeol Lee Korea Institute of Science and Technology, Seoul, Korea § Hanyang University, Seoul, Korea * Yonsei University, Seoul, Korea
Devices with Thin Multilayers 1~2nm GMR Spin Valve Major materials issue is the interfacial structurein atomic scale
Calculation Methods Adatom (normal incident 0.1 eV) 300K Initial Temperature 300K Constant Temperature Fixed Atom Position • Co-Al EAM potential* • x,y-axis : Periodic Boundary Condition • z-axis : Open Surface • Deposition rate:1.306 × 10-1 nm/nsec • MD calc. step : 0.1fs R. Pasianot et al, Phys. Rev. B45, 12704 (1992). A. F. Voter et al , MRS Proc. 82, 175 (1987). C. Vailhe et al, J. Mater. Res. 12, 2559 (1997).
Deposition in Co-Al System Co on Al (001) Al on Co (001)
3ML Al on Co(001) 3ML Co on Al(001) Asymmetry in Interfacial Intermixing
Radial Distribution Function of Interface • CoAl compound layer of B2 structure was formed spontaneously.
Atomic deposition behavior Co on Al(111) Al on Co(111)/(0001)
3ML Al on Co(001) 3ML Co on Al(001) Asymmetry in Interfacial Intermixing • Deposition at 300K • Initial kinetic energy 0.1eV
Spin-Up B2 - CoAl HCP - Co Spin-Down Magnetic Properties of Co-Al system FCC - Al Spin resolved DOS
Magnetic properties of Co-Al Thin Layer MOKE (Magneto-Optic Kerr effects) Capping layer (50Å) Capping layer (50Å) Capping layer (50Å) Co (30Å) Al (30Å) Co (30Å) Co (30Å) Cu buffer layer (1500Å) Al (840Å) Cu buffer layer (1500Å) Si substrate Si substrate Si substrate
Capping layer (50Å) Co (30Å, 5Å) Cu buffer layer (1500Å) Si substrate Co Thickness Effect
Capping layer (50Å) Al (30Å) Co (30Å) Cu buffer layer (1500Å) Co Si substrate Al Capping layer (50Å) Co (30Å) Al (840Å) Si substrate Effect of Coating Sequence Capping layer (50Å) Co (30Å) Cu buffer layer (1500Å) Si substrate Al
How thick is the nonmagnetic (B2) interlayer? 5Å 7Å 30Å 10Å
Thickness of B2 Layer : 3ML 3ML ~ 10Å
Summary Co on Al Al on Co Asymmetry in interfacial intermixing was observed in both MD simulation and experiment.
¯ ¯ 2ML Al on Co(1120) B2-like on Co(1120) Nano-scale Sandwich Structure Co/B2/Co A Novel Process
Acknowledgement Financial support from Core Capability Enhancement Program of KIST
3ML Al on Co(001) 3ML Co on Al(001) Asymmetry in Interfacial Intermixing • Deposition at 300K • Initial kinetic energy 0.1eV
Kinetic Criteria for Intermixing Activation Barrier for Mixing Reaction Coordinate
Co Al (1) (2) (3) (4) Kinetic Criteria for Intermixing Activation Barrier for Mixing Local Acceleration (1) 3.5eV (2) (3) (4) Reaction Coordinate
Deposition in Co-Al System Co on Al Al on Co
Co Al (1) (2) (3) (4) Kinetic Criteria for Intermixing Activation Barrier for Mixing Local Acceleration (1) 3.5eV (2) (3) (4) Reaction Coordinate