Large Magnetic Moment in Flexoelectronic Silicon at Room Temperature

TL;DR

This paper reports the first experimental detection of a large, room-temperature magnetic moment in silicon induced by flexoelectronic effects, opening new avenues for spintronic applications in non-magnetic semiconductors.

Contribution

It demonstrates that flexoelectronic polarization can generate significant magnetic moments in silicon, a phenomenon previously unobserved experimentally.

Findings

Magnetic moment up to 1.2 μ_B/atom detected in silicon.

Magnetic moment controlled by strain gradient, doping, and dopant.

Large magnetic moments achieved in non-magnetic, non-ferroelectric silicon.

Abstract

Time-dependent rotational electric polarizations have been proposed to generate temporally varying magnetic moments, for example, through a combination of ferroelectric polarization and optical phonons. This phenomenon has been called dynamical multiferroicity, but explicit experimental demonstrations have been elusive to date. Here, we report the detection of a temporal magnetic moment as high as 1.2 mu_B/atom in charge-doped thin film of silicon under flexural strain. We demonstrate that the magnetic moment is generated by a combination of electric polarization arising from a flexoelectronic charge separation along the strain gradient and the deformation potential of phonons. The effect can be controlled by adjusting the external strain gradient, doping concentration and dopant, and can be regarded as a dynamical multiferroic effect involving flexoelectronics polarization instead of ferroelectricity. The discovery of a large magnetic moment in silicon may enable the use of non-magnetic and non-ferroelectric semiconductors in various multiferroic and spintronic applications.