Maity, Tuhin and Goswami, Sudipta and Bhattacharya, Dipten and Roy, Saibal (2013) Superspin glass mediated giant spontaneous exchange bias in a nanocomposite of BiFeO3-Bi2Fe4O9. Physical Review Letters, 110 (10). Article No-107201. ISSN 0031-9007

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We observe an enormous spontaneous exchange bias (similar to 300-600 Oe)-measured in an unmagnetized state following zero-field cooling-in a nanocomposite of BiFeO3 (similar to 94%)-Bi2Fe4O9 (similar to 6%) over a temperature range 5-300 K. Depending on the path followed in tracing the hysteresis loop-positive (p) or negative (n)-as well as the maximum field applied, the exchange bias (H-E) varies significantly with vertical bar - H-Ep vertical bar > vertical bar H-En vertical bar. The temperature dependence of H-E is nonmonotonic. It increases, initially, till similar to 150 K and then decreases as the blocking temperature T-B is approached. All these rich features appear to be originating from the spontaneous symmetry breaking and consequent onset of unidirectional anisotropy driven by ``superinteraction bias coupling'' between the ferromagnetic core of Bi2Fe4O9 (of average size similar to 19 nm) and the canted antiferromagnetic structure of BiFeO3 (of average size similar to 112 nm) via superspin glass moments at the shell. DOI: 10.1103/PhysRevLett.110.107201

Item Type: Article
Subjects: Electronics
Divisions: Nano-Structured Materials
Depositing User: Bidhan Chaudhuri
Date Deposited: 12 Sep 2013 08:58
Last Modified: 12 Sep 2013 08:58

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