Specular Inverse Faraday Effect in Transition Metals

TL;DR

This study measures the inverse Faraday effect in various non-magnetic transition metals, revealing significant material-dependent differences and identifying conditions for enhanced opto-magnetic responses relevant for spintronics.

Contribution

It provides the first systematic time-resolved measurements of the inverse Faraday effect in non-magnetic metals, highlighting the role of material properties in the effect's magnitude.

Findings

W and Ta exhibit the largest inverse Faraday effect among studied metals.

The effect is significantly stronger in α-W compared to other metals.

Circular dichroism is induced in metals by circularly polarized light.

Abstract

The inverse Faraday effect is an opto-magnetic phenomenon that describes the ability of circularly polarized light to induce magnetism in solids. The capability of light to control magnetic order in solid state materials and devices is of interest for a variety of applications, such as magnetic recording, quantum computation and spintronic technologies. However, significant gaps in understanding about the effect persist, such as what material properties govern the magnitude of the effect in metals. In this work, we report time-resolved measurements of the specular inverse Faraday effect in non-magnetic metals, i.e., the magneto-optic Kerr effect induced by circularly polarized light. We measure this specular inverse Faraday effect in Cu, Pd, Pt, W, Ta, and Au at a laser wavelength of 783 nm. For Ta and W, we investigate both {\alpha} and \{beta} phases. We observe that excitation of these metals with circularly polarized light induces significant circular dichroism. This nonlinear magneto-optical response to circularly polarized light is an order of magnitude larger in {\alpha}-W than other metals, e.g., Pt, Au, and is greater than nearly all other reported values for IFE in other materials. Our results benchmark the range of IFE that can be observed in non-magnetic metals and provide insight into what material properties govern the inverse Faraday effect in metals.