Magnetization reversal of an individual exchange-biased permalloy nanotube

Buchter, A. and Wölbing, R. and Wyss, M. and Kieler, O. F. and Weimann, T. and Kohlmann, J. and Zorin, A. B. and Rüffer, D. and Matteini, F. and Tütüncüoglu, G. and Heimbach, F. and Kleibert, A. and Fontcuberta i Morral, A. and Grundler, D. and Kleiner, R. and Koelle, D. and Poggio, M.. (2015) Magnetization reversal of an individual exchange-biased permalloy nanotube. Physical Review B, 92 (21). p. 214432.

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We investigate the magnetization reversal mechanism in an individual permalloy (Py) nanotube (NT) using a hybrid magnetometer consisting of a nanometer-scale SQUID (nanoSQUID) and a cantilever torque sensor. The Py NT is affixed to the tip of a Si cantilever and positioned in order to optimally couple its stray flux into a Nb nanoSQUID. We are thus able to measure both the NT's volume magnetization by dynamic cantilever magnetometry and its stray flux using the nanoSQUID. We observe a training effect and a temperature dependence in the magnetic hysteresis, suggesting an exchange bias. We find a low blocking temperature TB=18±2 K, indicating the presence of a thin antiferromagnetic native oxide, as confirmed by x-ray absorption spectroscopy on similar samples. Furthermore, we measure changes in the shape of the magnetic hysteresis as a function of temperature and increased training. These observations show that the presence of a thin exchange-coupled native oxide modifies the magnetization reversal process at low temperatures. Complementary information obtained via cantilever and nanoSQUID magnetometry allows us to conclude that, in the absence of exchange coupling, this reversal process is nucleated at the NT's ends and propagates along its length as predicted by theory.
Faculties and Departments:05 Faculty of Science > Departement Physik > Physik > Nanotechnologie Argovia (Poggio)
UniBasel Contributors:Poggio, Martino and Buchter, Arne and Wyss, Marcus
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:American Physical Society
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:03 Aug 2018 15:14
Deposited On:10 May 2016 12:03

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