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Friday 14 Nov 2014Microwave magnonics at millikelvin

Dr. Alexy Karenowska - University of Oxford

Newman Red 12:00-13:00

The field of magnonics is the area of magnetics dedicated to the science of quasi-particles known as magnons - the quanta of magnetic excitations called spin waves. Spin waves can be thought of rather like a magnetic analogue of sound waves and commonly exist at microwave (gigahertz) frequencies [1]. In certain magnetic systems, magnons are able to play the role of microscopic tokens which carry spin - the quantum mechanical currency of magnetism - over relatively long distances (up to centimetres) and at high speed (many tens of kilometres per second).
Magnon spintronics - magnonics' emerging sister discipline - is concerned with structures and devices which involve the interconversion between electronic spin currents (that is, spin currents carried by electrons) and microwave-frequency magnon currents. Magnonic and magnon spintronic systems are not only a rich source of new physics, but potentially open doors to new electronic and information technologies.

This talk will begin with a general introduction to magnonics and magnon spintronics, and a perspective on their increasingly significant contributions to the understanding and technological application of fundamental magnetics [2-5]. Through a discussion of some recent results, we shall move on to examine the opportunities presented by the exploration of magnon dynamics at millikelvin temperatures; a new experimental direction which brings with it the promise both of unpicking quantum aspects of magnon and magnon spintronic physics with unprecedented clarity, and of investigating how this physics might play a role in future microwave quantum technologies.

[1] See for example the cluster issue on magnonics, J. Phys. D: Appl. Phys., 43, (2010).
[2] M. B. Jungfleisch et al., Appl. Phys. Lett., 99 182512, (2011).
[3] A. D. Karenowska, V. S. Tiberkevich, A. V. Chumak, A. A. Serga, J. F. Gregg, A. N. Slavin, and B. Hillebrands, Phys. Rev. Lett., 108 015505, (2012).
[4] A. V. Chumak, V. S. Tiberkevich, A. D. Karenowska, A. A. Serga, J. F. Gregg, A. N. Slavin, and B. Hillebrands, Nature Commun., 1 141, (2010).
[5] M. Agrawal, V. I. Vasyuchka, A. A. Serga, A. D. Karenowska, G. A. Melkov, and B. Hillebrands, Phys. Rev. Lett., 111 107204, (2013).

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