Abstract
Diluted magnetic semiconductors (DMSs), with the Curie temperature at room temperature, are of technological and fundamental importance. Defect engineering has been an effective way to introduce magnetic moments in various non-magnetic systems. Here we show firstly, InN film directly grown on (0001)-oriented Al2O3 substrate with In deficiency is ferromagnetic with its Curie temperature as high as 297K. The undesirable large lattice mismatch between the film and substrate leads to a peculiar surface structure that the film separates into distinct In-rich and In-poor regions. Our first-principles calculations suggest the defect of In-vacancy is responsible for the magnetism. A local magnetic moment of 2.5μB is found, in agreement with experimental results. Our findings demonstrate that room-temperature ferromagnetism can also be induced in narrow band gap semiconductors through defect engineering, which remains largely unexplored so far.
Highlights
III-nitrides-based diluted magnetic semiconductors (DMSs) have attracted great attention due to their potential applications in the emerging field of spintronics
Despite of some very promising results in the literature, the precipitation of second phases or clusters[3] due to poor solubility of magnetic elements may limit the application of DMS and complicate the explanation of magnetic signals
Defects are responsible for various other systems with no transition metal (TM)-element-doped, such as ZnO,[5] CaO,[6] Nb-doped TiO27 and carbon structures[8] etc., which show rather sensitive dependence of magnetism on defects
Summary
III-nitrides-based diluted magnetic semiconductors (DMSs) have attracted great attention due to their potential applications in the emerging field of spintronics. Defect-induced room temperature ferromagnetism in un-doped InN film S. Wua Lab of Solid State Microstructure, Nanjing University, Nanjing 210093, China (Received 18 January 2012; accepted 1 March 2012; published online 23 March 2012)
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