Letter abstract

Nature Nanotechnology 3, 720 - 723 (2008)
Published online: 2 November 2008 | doi:10.1038/nnano.2008.311

Subject terms: Nanomagnetism and spintronics | NEMS

Nanomechanical detection of itinerant electron spin flip

Guiti Zolfagharkhani1, Alexei Gaidarzhy2, Pascal Degiovanni1,3, Stefan Kettemann4, Peter Fulde5 & Pritiraj Mohanty1

Electrons and other fundamental particles have an intrinsic angular momentum called spin. A change in the spin state of such a particle is therefore equivalent to a mechanical torque. This spin-induced torque is central to our understanding of experiments1, 2 ranging from the measurement of the angular momentum of photons3 and the g-factor of metals4, 5, 6, 7 to magnetic resonance8 and magnetization reversal in magnetic multilayers8, 9, 10, 11, 12, 13, 14, 15. When a spin-polarized current passes through a metallic nanowire in which one half is ferromagnetic and the other half is nonmagnetic, the spins of the itinerant electrons are ‘flipped’ at the interface between the two regions to produces a torque. Here, we report direct measurement of this mechanical torque in an integrated nanoscale torsion oscillator, and measurements of the itinerant electron spin polarization that could yield new information on the itinerancy of the d-band electrons. The unprecedented torque sensitivity of 1 × 10−22 N-m Hz−1/2 may have applications in spintronics and precision measurements of charge–parity-violating forces16, 17, and might also enable experiments on the untwisting of DNA18 and torque-generating molecules19, 20.

  1. Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA
  2. Department of Mechanical and Aerospace Engineering, Boston University, 110 Cummington Street, Boston, Massachusetts 02215, USA
  3. Université de Lyon, Fédération de Physique André Marie Ampère, CNRS-Laboratoire de Physique de l'Ecole Normale, Supérieure de Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France
  4. Jacobs University Bremen, School of Engineering and Science, Campus Ring 1, D-28759 Bremen, Germany
  5. Asia Pacific Centre for Theoretical Physics, Namgu Pohang, Gyeongbuk 790-784, Korea

Correspondence to: Pritiraj Mohanty1 e-mail: mohanty@physics.bu.edu