Regular Nanowire Formation on Fe-Based Metal Glass by Manipulation of Surface Waves

Zhen Zhao,Chaoqun Xia,Jianjun Yang

doi:10.3390/nano11092389

Abstract

We report the formation of a sole long nanowire structure and the regular nanowire arrays inside a groove on the surface of Fe-based metallic glass upon irradiation of two temporally delayed femtosecond lasers with the identical linear polarization parallel and perpendicular to the groove, respectively. The regular structure formation can be well observed within the delay time of 20 ps for a given total laser fluence of F = 30 mJ/cm2 and within a total laser fluence range of F = 30–42 mJ/cm2 for a given delay time of 5 ps. The structural features, including the unit width and distribution period, are measured on a one-hundred nanometer scale, much less than the incident laser wavelength of 800 nm. The degree of structure regularity sharply contrasts with traditional observations. To comprehensively understand such phenomena, we propose a new physical model by considering the spin angular momentum of surface plasmon and its enhanced inhomogeneous magnetization for the ferromagnetic metal. Therefore, an intensive TE polarized magnetic surface wave is excited to result in the nanometer-scaled energy fringes and the ablative troughs. The theory is further verified by the observation of nanowire structure disappearance at the larger time delays of two laser pulses.

Highlights

Accepted: 6 September 2021The creation of micro and nanoscale structures is known as a cornerstone for the development of modern photonics because it possesses capabilities in manipulating optical properties of materials for the improved performance of devices [1,2]
The recent advancements of femtosecond laser applications have clearly demonstrated an alternative potential for the large-area production of the periodic structures in subwavelength or even nanometer scales with a convenient mask-free way, which are verified on a variety of materials, including metals [5,6,7,8,9,10,11,12,13,14], semiconductors [15,16,17], and dielectrics [18,19,20,21]
We investigate an intriguing formation of the nanowire structures within a pre-fabricated groove on Fe-based metallic glass, using two time-delayed femtosecond laser beams linearly polarized in the same direction

Summary

Introduction

Accepted: 6 September 2021The creation of micro and nanoscale structures is known as a cornerstone for the development of modern photonics because it possesses capabilities in manipulating optical properties of materials for the improved performance of devices [1,2]. For the solid metallic materials, the laser-induced periodic surface structures (LIPSSs) are usually categorized into the low-spatial-frequency (LSF) and the high-spatialfrequency (HSF) types [5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21]. In the former case, the structures often exhibit a spatial period (Λ) close to the incident laser wavelength (λ), i.e., (λ/2 < Λ < λ), associated with orientation perpendicular to the direction of the light polarization.

Methods

Results

Conclusion