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There is now a CONTENT FREEZE for Mercury while we switch to a new platform. It began on Friday, March 10 at 6pm and will end on Wednesday, March 15 at noon. No new content can be created during this time, but all material in the system as of the beginning of the freeze will be migrated to the new platform, including users and groups. Functionally the new site is identical to the old one. webteam@gatech.edu
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Conservation of the total angular momentum, spin + mechanical, requires coupling between mechanical rotation of a body and magnetic moments inside the body, known as the Einstein – de Haas effect. Microscopic mechanisms of this effect vary for different systems. Motion of domain walls dominates the magneto-mechanical coupling in microcantilevers [1,2]. Spins provide universal damping mechanism for the mechanical motion of a nanocantilever [3]. Non-trivial quantum mechanics of the angular momentum exists in magnetic molecules that have full or partial mechanical freedom [4]. Coupled quantum dynamics of a spin and a mechanical resonator explains recent experiments with single magnetic molecules grafted onto a carbon nanotube [5]. The concept of the phonon spin becomes useful in the analysis of the conservation of angular momentum in spin-phonon processes [6]. A solid containing two-state systems, magnetic molecules in particular, may exhibit measurable forces of quantum origin [7]. Spin mechanics problems of practical interest include switching of the magnetic moment in a nanoresonator by the combined effect of the spin-polarized current and mechanical kick [8], possibility of the electromechanical magnetization switching in multiferroics [9], and switching of the magnetization by surface acoustic waves [10]. This research has been supported by grants from the U.S. National Science Foundation.
References: [1] R. Jaafar, E. M. Chudnovsky, and D. A. Garanin, Dynamics of Einstein - de Haas Effect: Application to Magnetic Cantilever, Phys. Rev. B 79, 104410 (2009). [2] S-H. Lim, A. Imtiaz, T. M. Wallis, S. Russek, P. Kabos, L. Cai, and E. M. Chudnovsky, Magneto-Mechanical Investigation of Spin Dynamics in Magnetic Multilayers, Europhys. Lett. 105, 37009 (2014). [3] E. M. Chudnovsky and D. A. Garanin, Damping of a Nanocantilever by Paramagnetic Spins, Phys. Rev. B 89, 174420 (2014). [4] E. M. Chudnovsky, Spin Tunneling in Magnetic Molecules that Have Full or Partial Mechanical Freedom (Ch. 3 in “Molecular Magnets: Physics and Applications”, Springer 2014). [5] M. F. O’Keeffe, E. M. Chudnovsky, and D. A. Garanin, Landau-Zener Dynamics of a Nanoresonator Containing a Tunneling Spin, Phys. Rev. B 87, 174418 (2013). [6] D. A. Garanin and E. M. Chudnovsky, Angular Momentum in Spin-Phonon Processes, Phys. Rev. B 92, 024421 (2015). [7] E. M. Chudnovsky, J. Tejada, and R. Zarzuela, Quantum Forces in Solids with Two-State Systems: An Example of a Molecular Magnet, Phys. Rev. B 88, 220409(R) (2013). [8] L. Cai, R. Jaafar, and E. M. Chudnovsky, Mechanically-Assisted Current-Induced Switching of the Magnetic Moment in a Torsional Oscillator, Phys. Rev. Appl. 1, 054001 (2014). [9] E. M. Chudnovsky and R. Jaafar, Electromechanical Magnetization Switching, J. Appl. Phys. 117, 103910 (2015). [10] E. M. Chudnovsky and R. Jaafar, Magnetization Reversal by Surface Acoustic Waves, to be published.
