[22a-B201-1~11] 10.1 新物質・新機能創成（作製・評価技術）

▲ [22a-B201-6] Autonomous material search for highly spin-polarized disordered material: Enhanced spin-polarization of CoFe upon Ag substitution

〇(P)Varun Kumar Kushwaha¹、Y. Iwasaki¹、T. Nakatani¹、T. Sasaki¹、S. Kasai¹、K. Uchida¹、Y. Sakuraba¹ (1.NIMS)

キーワード：Spintronics materials, Half-metallic ferromagnets, Autonomous materials search technique

Although half-metallic Heusler alloys are one of the representative materials that have been proved to show high spin-polarization (P), the necessity of a high degree of atomic orders often causes difficulty for practical applications. Using an autonomous materials search technique by combining a machine learning method and ab-initio calculation, we efficiently searched novel highly spin-polarized material having atomic disordered bcc and fcc structure from vast material search space. The developed autonomous material search system discovered that bcc CoFe-Ag often shows a half-metallic nature and the highest P ~ 96% is obtained in Co_0.1Fe_0.6Ag_0.3. To investigate the Ag dependency on P of CoFe alloy experimentally, (CoFe)_1-xAg_x (x = 0-0.4) composition-spread films were fabricated into non-local spin-valve devices. Interestingly, the spin-polarization of electric current was enhanced by about 10% with respect to the Co_0.143Fe_0.857 alloy with Ag substitution up to x = 0.2.