Low-frequency magnetic and resistance noise in magnetoresistive tunnel junctions

Lai Jiang; Jonathan F. Skovholt; Edmund R. Nowak; Jon M. Slaughter

doi:10.1117/12.544659

25 May 2004 Low-frequency magnetic and resistance noise in magnetoresistive tunnel junctions

Lai Jiang, Jonathan F. Skovholt, Edmund R. Nowak, Jon M. Slaughter

Proceedings Volume 5469, Fluctuations and Noise in Materials; (2004) https://doi.org/10.1117/12.544659
Event: Second International Symposium on Fluctuations and Noise, 2004, Maspalomas, Gran Canaria Island, Spain

Abstract

We report on the voltage fluctuations in exchange-biased, micron-scale magnetic tunnel junctions. We find that the spectral power density is 1/f-like at low frequencies and becomes frequency independent at high frequencies. The frequency-independent background noise is due to thermal and shot noise mechanisms. The nature of the 1/f noise has its origin to two different mechanisms. In the magnetic hysteresis loops this noise power is strongly field-dependent and is due to thermal magnetization fluctuations in both the 'free' and 'fixed' magnetic layers. We attribute these magnetic fluctuations to thermally excited hopping of magnetic domain walls between pinning sites. A second mechanism for the 1/f noise, connected with defects in the tunnel barrier but not related to the overall magnetization fluctuations, was found at fields for which the magnetic structure in the free and fixed layers is well aligned. This noise is associated with electron trapping processes having thermally activated kinetics and a broad distribution of activation energies. Below ~ 25 K the noise power is temperature independent suggesting that the kinetics are dominated by tunneling. Our results show that the thermal stability of the both magnetic layers and the quality of the tunnel barrier are important factors in reducing the low-frequency noise in magnetic tunnel junctions.

Citation Download Citation

Lai Jiang, Jonathan F. Skovholt, Edmund R. Nowak, and Jon M. Slaughter "Low-frequency magnetic and resistance noise in magnetoresistive tunnel junctions", Proc. SPIE 5469, Fluctuations and Noise in Materials, (25 May 2004); https://doi.org/10.1117/12.544659

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