Magnetic field generation with helical laser beams in electron-hole plasmas

¹ Department of Applied Physics, Federal Urdu University of Arts, Science and Technology - Kuri Road, Islamabad, Pakistan
² National Centre for Physics at QAU Campus, CoE Physics - Shahdra Valley Road, Islamabad 44000, Pakistan
³ SUPA, Physics Department, University of Strathclyde - Glasgow G4 0NG, Scotland, UK

Received: 18 February 2025
Accepted: 14 May 2025

Abstract

A circularly polarized Laguerre-Gaussian (LG) laser beam moves in an electron-hole plasma, producing a quasi-static magnetic field in azimuthal direction. To achieve this, electron and hole momentum equations are solved taking non-relativistic ponderomotive and Lorentz forces on equal footing. However, the present model neglects quantum effects for low-carrier densities and high temperatures, also omitting electron-hole thermal pressures compared with ponderomotive force. Electron and hole velocities move along the z-axis to generate the current density according to Ampère's law, resulting in the azimuthal magnetic field. The latter strongly depends on laser intensity and confirms its behavior in typical semiconducting materials. A high degree of agreement between the analytical and numerical results is found, supporting the validity of the analytical method. Numerically, it is shown that azimuthal and radial mode numbers, pulse amplitude, and hole-to-electron effective mass ratios significantly modify the magnetic field profiles. The present findings only validate a non-relativistic classical electron-hole plasma for which the carrier density must be smaller than the critical density .