Exchange-dominated eigenmodes in sub-100 nm permalloy dots: A micromagnetic study at finite temperature

Carlotti, G., Gubbiotti, G., Madami, M., Tacchi, S. and Stamps, R. L. (2014) Exchange-dominated eigenmodes in sub-100 nm permalloy dots: A micromagnetic study at finite temperature. Journal of Applied Physics, 115(17), 17D119. (doi: 10.1063/1.4862844)

Abstract

Micromagnetic simulations at room temperature (300 K) have been carried out in order to analyse the magnetic eigenmodes (frequency and spatial profile) in elliptical dots with sub-100 nm lateral size. Features are found that are qualitatively different from those typical of larger dots because of the dominant role played by the exchange-energy. These features can be understood most simply in terms of nodal planes defined relative to the orientation of the static magnetization. A new, generalized labeling scheme is proposed that simplifies discussion and comparison of modes from different geometries. It is shown that the lowest-frequency mode for small dots is characterized by an in-phase precession of spins, without nodal planes, but with a maximum amplitude at the edges. This mode softens at an applied switching field with magnitude comparable to the coercive field and determines specific aspects of magnetization reversal. This characteristic behavior can be relevant for optimization of microwave assisting switching as well as for maximizing interdot coupling in dense arrays of dots.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Stamps, Professor Robert
• Authors: Carlotti, G., Gubbiotti, G., Madami, M., Tacchi, S., and Stamps, R. L.
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Journal Name: Journal of Applied Physics
• Publisher: American Institute of Physics
• ISSN: 0021-8979
• ISSN (Online): 1089-7550