Magnetic hardness features and loop shift in nanostructured CuO

• Published in: Journal of applied physics Vol. 112; no. 8
• Main Authors: Bianchi, A. E., Stewart, S. J., Zysler, R. D., Punte, G.
• Format: Journal Article
• Language: English
• Published: 15.10.2012
• Subjects: BALL MILLS; Bulk sampling; COMPOSITES; COPPER OXIDE; CUPRIC OXIDE; Displays; Hardness; MAGNETIC PROPERTIES; MICROSTRUCTURES; Multilayers; Nanocomposites; Nanomaterials; Nanostructure; OXIDES; SAMPLING
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.4758307

Nanostructures of cupric oxide (CuO) obtained by ball milling show drastic changes in its magnetic behavior that cannot be only associated to a size effect. While sample of average size D = 29 nm presents a magnetic behavior that resembles that of bulk material with a Néel temperature of 195 K, another sample with D = 24 nm displays a departure from the magnetic features typical of bulk CuO and has magnetic hardness characteristics at low temperatures. Both samples show irreversibility above room temperature and shifts in their hysteresis loops along magnetization and field axis when field cooled in a HFC = 50 kOe to 10 K. At this temperature, an apparent exchange bias like field, “HEB”, 0.17 and 1.06 kOe were estimated for 29 and 24 nm CuO samples, respectively. Magnetic behavior differences observed in samples subjected to distinct milling times are explained as due to a proposed model for milled CuO consisting of a multilayer configuration where interfaces comprise uneven structural disorder and oxygen deficiencies, which generate a peculiar antiferromagnetic/ferromagnetic interface configuration.