Eur. Phys. J. B 82, 167-171 (2011)
https://doi.org/10.1140/epjb/e2011-20364-x

Quantum coherent effect of spins in magnetic nanodots

Physics Department, Beijing University of Science & Technology, Beijing, 100083, P.R. China

Corresponding author: ^a fengpeng@ustb.edu.cn

Received: 12 May 2011
Revised: 16 May 2011
Published online: 5 August 2011

Abstract

We study a quantum coherent effect of spins in magnetic nanodots. We quantize the Heisenberg Hamiltonian in a coherent representation so as to deal with the time evolution of spin components. We observe that the number of quantum states in a nanodot is dependent on the nanodot size. For a nanodot of small size, it has very rare quantum states with a discrete energy structures. The distribution patterns of spins in these quantum states rotate about a central axis normal to the nanodot plane, and the spin reversal occurs with time. These quantum states can be achieved by a resonant excitation of a time-varying magnetic field. As a suggestion, the reversal of coherent spins may serve as a mechanism of binary information storage.