title: High-Tc ferromagnetic semiconductor-like behavior and unusual electrical properties in compounds with a 2×2×2 superstructure of the half-Heusler phase.
abstract: Heusler phases, including the full- and half-Heusler families, represent an outstanding class of multifunctional materials on account of their great tunability in compositions, valence electron counts (VEC), and properties. Here we demonstrate a systematic design of a series of new compounds with a 2×2×2 superstructure of the half-Heusler unit cell in X-Y-Z (X=Fe, Ru, Co, Rh, Ir; Y=Zn, Mn; Z=Sn, Sb) systems. Their structures were solved by using both powder and single-crystal X-ray diffraction, and also directly observed by using high-angle annular dark-field imaging in a scanning transmission electron microscope (HAADF-STEM). The VEC values of these new compounds span a wide and continuous range comparable to those for the full- and half-Heusler families, thereby implying tunability in compositions and physical properties in the superstructure. In fact, we observed abnormal electrical properties and a ferromagnetic semiconductor-like behavior with a high and tunable Curie temperature in these superstructures.
authors.affiliation: Department of Materials Science and Engineering, Kyoto University, Kyoto 606-8501, Japan. xiong.dingbang@ky8.ecs.kyoto-u.ac.jp
authors.forename: Ding-Bang
authors.initials: DB
authors.lastname: Xiong
authors.forename: Norihiko L
authors.initials: NL
authors.lastname: Okamoto
authors.forename: Takeshi
authors.initials: T
authors.lastname: Waki
authors.forename: Yufeng
authors.initials: Y
authors.lastname: Zhao
authors.forename: Kyosuke
authors.initials: K
authors.lastname: Kishida
authors.forename: Haruyuki
authors.initials: H
authors.lastname: Inui