Magnetic nanodots from atomic Fe: Can it be done?

doi:10.1073/pnas.072525199

Magnetic nanodots from atomic Fe: Can it be done?

Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands

Edited by Jack Halpern, University of Chicago, Chicago, IL, and approved February 7, 2002 (received for review October 5, 2001)

Abstract

Laser focusing of Fe atoms offers the possibility of creating separate magnetic structures on a scale of 10 nm with exact periodicity. This can be done by using the parabolic minima of the potential generated by a standing light wave as focusing lenses. To achieve the desired 10-nm resolution, we need to suppress chromatic and spherical aberrations, as well as prevent structure broadening caused by the divergence of the incoming beam. Chromatic aberrations are suppressed by the development of a supersonic Fe beam source with speed ratio S = 11 ± 1. This beam has an intensity of 3 × 10¹⁵ atoms sr⁻¹ s⁻¹. The spherical aberrations of the standing light wave will be suppressed by aperturing with beam masks containing 100-nm slits at 744-nm intervals. The beam divergence can be reduced by application of laser cooling to reduce the transverse velocity. We have constructed a laser system capable of delivering over 500 mW of laser light at 372 nm, the wavelength of the ⁵D₄ → ⁵F₅ atomic transition of ⁵⁶Fe we intend to use for laser cooling. Application of polarization spectroscopy to a hollow cathode discharge results in a locking system holding the laser continuously within 2 MHz of the desired frequency.

Footnotes

↵ † To whom reprint requests should be addressed. E-mail: e.t.sligte{at}tue.nl.
This paper results from the Arthur M. Sackler Colloquium of the National Academy of Sciences, “Nanoscience: Underlying Physical Concepts and Phenomena,” held May 18–20, 2001, at the National Academy of Sciences in Washington, DC.
This paper was submitted directly (Track II) to the PNAS office.