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標題: Exchange bias in a nanocolumnar Ni80Fe20/alpha-Fe2O3 thin film
作者: van Lierop, J.
Lin, K.W.
Guo, Z.Y.
Ko, P.H.
Ouyang, H.
關鍵字: temperature;bilayers
Project: Journal of Applied Physics
期刊/報告no:: Journal of Applied Physics, Volume 101, Issue 9.
A Ni80Fe20/alpha-Fe2O3 thin film has been deposited using a dual ion-beam deposition technique where the alpha-Fe2O3 is formed in situ by O-2 bombardment of pure Fe. AC susceptibility results indicate moment fluctuations at temperatures above 150 K. This behavior combined with the thermal fluctuation driven temperature dependence of the negative field coercivity indicates that the alpha-Fe2O3 nanocolumnar crystallite magnetism evolves from static single domain moments to superparamagnetic moments with warming. 25 kOe field cooling establishes exchange bias with an onset temperature of 50 K. The positive (H-c2) and negative (H-c1) field coercivities exhibit very different temperature dependencies, with H-c1(T) well described by a thermally activated coherent domain wall reversal model, while H-c2(T) is essentially constant except for the lowest temperatures. These results point towards different domain reversal mechanisms in positive and negative fields.
ISSN: 0021-8979
DOI: 10.1063/1.2672440
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