Laser-induced spin protection and switching in a specially designed magnetic dot: A theoretical investigation

¹ Department of Physics, Indiana State University - Terre Haute, IN 47809, USA
² Office of the Chancellor and Center for Nanoscience, Departments of Chemistry & Biochemistry and Physics & Astronomy, University of Missouri-St. Louis - St. Louis, MO 63121, USA

^a gpzhang@indstate.edu

Received: 22 October 2010
Accepted: 8 March 2011

Abstract

Most laser-induced femtosecond magnetism investigations are done in magnetic thin films. Nanostructured magnetic dots, with their reduced dimensionality, present new opportunities for spin manipulation. Here we predict that if a magnetic dot has a dipole-forbidden transition between the lowest occupied molecular orbital (LUMO) and the highest unoccupied molecular orbital (HOMO), but a dipole-allowed transition between LUMO+1 and HOMO, electromagnetically induced transparency can be used to prevent ultrafast laser-induced spin momentum reduction, or spin protection. This is realized through a strong dump pulse to funnel the population into LUMO+1. If the time delay between the pump and dump pulses is longer than 60 fs, a population inversion starts and spin switching is achieved. These predictions are detectable experimentally.