Title: Femtosecond laser machining of high permeability permalloy

Authors: Xiaoping Li; Minghui Hong

Addresses: Department of Mechanical Engineering, National University of Singapore, 117576, Singapore ' Department of Electrical and Computer Engineering, National University of Singapore, 117576, Singapore

Abstract: For the multi-core orthogonal fluxgate magnetic field sensor, in which the sensor sensitivity increases exponentially with the number of cores in the sensing element, a micro/nano multi-core structured high permeability magnetic material, such as permalloy, is expected. A permalloy sheet can be formed into such a multi-core structure material by laser machining if the magnetic properties are not damaged. In this study, the effects of femtosecond laser machining of permalloy on the magnetic properties of the machined permalloy workpiece are investigated. The results show that changes in the coercivity of the machined permalloy workpiece are dependent on the surface morphology modification induced by the femtosecond laser. It appears that there is a laser fluence threshold for the permalloy coercivity to decrease to a minimum (as indicated by the formation of ripples on the machined surface), beyond which the coercivity will increases with the laser fluence at a gradual rate.

Keywords: femtosecond laser machining; permalloys; laser fluence; coercivity; permeability; machined surface; magnetic field sensors; magnetic properties; permalloy sheet.

DOI: 10.1504/IJAT.2012.052035

International Journal of Abrasive Technology, 2012 Vol.5 No.4, pp.332 - 340

Received: 04 Jun 2012
Accepted: 24 Jun 2012

Published online: 04 Feb 2013 *

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