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High‐ T C Ferromagnetic Semiconductor‐Like Behavior and Unusual Electrical Properties in Compounds with a 2×2×2 Superstructure of the Half‐Heusler Phase
Author(s) -
Xiong DingBang,
Okamoto Norihiko L.,
Waki Takeshi,
Zhao Yufeng,
Kishida Kyosuke,
Inui Haruyuki
Publication year - 2012
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201102939
Subject(s) - superstructure , materials science , ferromagnetism , valence (chemistry) , curie temperature , transmission electron microscopy , condensed matter physics , semiconductor , scanning transmission electron microscopy , crystallography , nanotechnology , optoelectronics , chemistry , oceanography , physics , organic chemistry , geology
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.