[8a-P05-1~21] 6.4 Thin films and New materials

English Presentation

[8a-P05-12] Solid-State dewetting in L1₀-FePd epitaxial films by a two-step heating method

Vergara Samuel⁵, Shingo Maruyama¹, Soki Yoshida², Keisuke Haruki¹, Naoya Matsumoto², Mitsuharu Uemoto³, Tomoya Ono³, Shintaro Yasui⁴, Yasushi Endo¹, Masaki Mizuguchi², Tomoyuki Ogawa¹, 〇Hiroshi Naganuma² (1.Tohoku Univ., 2.Nagoya Univ., 3.Kobe Univ., 4.Sci.Tokyo, 5.Univ. Paris-Saclay)

Keywords:

L10-FePd,Solid-State dewetting,Two step heating

L1₀-FePd alloy films with a design thickness of 5 nm were grown by r.f. magnetron sputtering on SrTiO₃ (001) single crystal substrates by a 2-step heating method. The initial crystal growth mechanism of L1₀-FePd epitaxial films was drastically changed into the following 3 patterns (i) ~ (iii), even by a slight change of 1^st growth temperature in a 2-step heating process. (i) Almost no lattice disturbance in the in-plane direction was observed, and perfect constraint by tensile strain from the substrate was achieved. Furthermore, owing to the Frank–van der Merwe (FM) of lateral growth mode and without dislocations, an atomically flat surface was realized. (ii) Solid-state dewetting occurred due to the thin film thickness of 5 nm and the two-fold difference in surface free energy between SrTiO₃ and L1₀-FePd. Film retreating due to solid-state dewetting occurred along the crystal orientation of the SrTiO₃ substrate. (iii) The grains grew by 3-dimensionally which is typically categorized by the Stranski-Krastanov (SK) or Volmer-Weber (VW) growth mode. Note that the 1^st growth temperature of the 2-step heating significantly changed the initial growth mode, even though the 2^nd heating temperature of 600°C was significantly higher than that of the 1^st growth temperature (T_s = 150 - 300°C). The solid-state dewetting reduced the substrate restraint, resulting in the highest degree of L1₀-ordering and the highest perpendicular magnetic anisotropy.