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Tunable quantum tunnelling of magnetic domain walls

Brooke, J. and Rosenbaum, T. F. and Aeppli, G. (2001) Tunable quantum tunnelling of magnetic domain walls. Nature, 413 (6856). pp. 610-613. ISSN 0028-0836. doi:10.1038/35098037.

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Perhaps the most anticipated, yet experimentally elusive, macroscopic quantum phenomenon is spin tunnelling in a ferromagnet, which may be formulated in terms of domain wall tunnelling. One approach to identifying such a process is to focus on mesoscopic systems where the number of domain walls is finite and the motion of a single wall has measurable consequences. Research of this type includes magnetotransport measurements on thin ferromagnetic wires, and magnetization experiments on single particles, nanomagnet ensembles and rare-earth multilayers. A second method is to investigate macroscopic disordered ferromagnets, whose dynamics are dominated by domain wall motion, and search the associated relaxation-time distribution functions for the signature of quantum effects. But whereas the classical, thermal processes that operate in these experiments are easily regulated via temperature, the quantum processes have so far not been tunable, making difficult a definitive interpretation of the results in terms of tunnelling. Here we describe a disordered magnetic system for which it is possible to adjust the quantum tunnelling probabilities. For this material, we can model both the classical, thermally activated response at high temperatures and the athermal, tunnelling behaviour at low temperatures within a unified framework, where the domain wall is described as a particle with a fixed mass. We show that it is possible to tune the quantum tunnelling processes by adjusting the `mass' of this particle with an external magnetic field.

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Additional Information:© 2001 Macmillan Publishers Limited. Received 22 December 2000; accepted 16 August 2001. We thank D. Bitko, S. Girvin, S. Nagel, P. Stamp and T. Witten for discussions. The work at the University of Chicago was supported primarily by the MRSEC Program of the National Science Foundation.
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Issue or Number:6856
Record Number:CaltechAUTHORS:20140707-163030837
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:46967
Deposited By: George Porter
Deposited On:14 Jul 2014 16:38
Last Modified:10 Nov 2021 17:32

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