Structure and magnetic behavior of CoPt films prepared on MgO(001) substrates by dc plasma biased sputtering

• Published in: Thin solid films Vol. 459; no. 1; pp. 165 - 168
• Main Authors: Yamaguchi, Kenrou, Zhao, Zhongyu, Chen, Changchuan, Hashimoto, Mituru, Shi, Ji, Nakamura, Yoshio
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Lausanne Elsevier B.V 01.07.2004; Elsevier Science
• Subjects: Coercivity; CoPt alloy; Cross-disciplinary physics: materials science; rheology; Deposition by sputtering; Exact sciences and technology; L1o structure; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Perpendicular magnetic anisotropy; Physics; Sputtering; 68.55-a; CoPt alloy; 75.50Kj; 75.50Vv; 81.15Cd; L1o structure; Coercivity; Sputtering; 75.20En; 81.10-h; 75.30Gw; 75.70Ak; Perpendicular magnetic anisotropy; FCC lattices; Inorganic compounds; Films; Ferromagnetic materials; Crystal growth from vapors; XRD; 81.15Cd CoPt alloy; Cathode sputtering; Coercive force; Thermal annealing; Magnetization; Platinum alloys; Experimental study; Llo structure; Interfaces; Binary alloys; Transmission electron microscopy; Anisotropy; Cobalt alloys; Transition element alloys
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2003.12.124

CoPt films were prepared on MgO(001) substrates at 230 °C by d.c. sputtering. Both films on the unbiased and the biased (−150 V) substrates grow with the crystallographic orientation of CoPt(001)[100]//MgO(001)[100]. In fact, the unbiased film is deformed from the perfect face-centered cubic (fcc) structure towards the face-centered tetragonal (fct) structure with an incomplete ordered phase, while the biased film retains normally the fcc structure. Both films show the in-plane magnetic anisotropy with coercivity less than 1000 Oe. Upon the thermal anneal at 800 °C×30 min, the unbiased film is transformed completely into the L1o-fct structure while the biased film is transformed into the fct structure but not completely into the complete L1o structure. The unbiased film shows clearly the perpendicular magnetic anisotropy with the squareness equal to unity, while the biased film shows only the weaker perpendicular magnetic anisotropy with the squareness less than 0.7. The perpendicular coercivity is estimated at 3200 Oe for the unbiased film and 2200 Oe for the biased film.