Working Paper Article Version 1 This version is not peer-reviewed

# Ablation patterns in externally applied electric and magnetic fields

Version 1 : Received: 15 January 2020 / Approved: 16 January 2020 / Online: 16 January 2020 (11:08:18 CET)

A peer-reviewed article of this Preprint also exists.

Maksimovic, J.; Ng, S.-H.; Katkus, T.; An Le, N.H.; Chon, J.W.M.; Cowie, B.C.C.; Yang, T.; Bellouard, Y.; Juodkazis, S. Ablation in Externally Applied Electric and Magnetic Fields. Nanomaterials 2020, 10, 182. Maksimovic, J.; Ng, S.-H.; Katkus, T.; An Le, N.H.; Chon, J.W.M.; Cowie, B.C.C.; Yang, T.; Bellouard, Y.; Juodkazis, S. Ablation in Externally Applied Electric and Magnetic Fields. Nanomaterials 2020, 10, 182.

Journal reference: Nanomaterials 2020, 10, 182
DOI: 10.3390/nano10020182

## Abstract

To harness light-matter interaction at nano-/micro-scale better control tools have to be developed. Here, it is shown that by applying external electric and/or magnetic field, ablation of Si and glass under ultra-short (sub-1~ps) laser pulse irradiation can be controlled via the Lorentz force $\mathbf{F} = e\mathbf{E} + e[\mathbf{v}\times\mathbf{B}]$, where $\mathbf{v}$ is velocity of charge $e$, $\mathbf{E}$ is the applied electrical bias and $\mathbf{B}$ is the magnetic flux density. The external electric E-field was applied during laser ablation using suspended micro-electrodes above glass substrate with an air gap for the incident laser beam. The counter-facing Al-electrodes on Si surface were used to study debris formation patterns on Si. Debris was deposited preferentially towards the negative electrode in the case of glass and Si ablation. Also, an external magnetic field was applied during laser ablation of Si in different geometries and is shown to affect ripple formation. The vectorial nature of the Lorentz force widens application potential of surface modifications and debris formation in external E-/B-fields with potential applications in mass and charge spectroscopes.

## Subject Areas

ablation; electric field; magnetic field; debris; femtosecond laser fabrication; Silicon; near edge X-ray absorption fine structure (NEXAFS)