New magnetic component discovered in the Faraday effect after nearly two centuries

Amazing stuff!

"Researchers at the Hebrew University of Jerusalem discovered that the magnetic component of light plays a direct role in the Faraday effect, overturning a 180-year-old assumption that only its electric field mattered. ...

It presents the first theoretical proof that the oscillating magnetic field of light directly contributes to the Faraday effect, a phenomenon in which the polarization of light rotates as it passes through a material exposed to a constant magnetic field. ..."

From the abstract:

"The Faraday effect (FE) is commonly attributed to the electrical component of optical radiation. Recently, we reported on an inverse-FE (IFE) that emerges from the Zeeman energy arising from the optical magnetic field.

Here, we show that the magnetic component of light reproduces additional signatures observed experimentally in the IFE. Consequently, we show that the magnetic component of light also contributes to the reciprocal, direct FE. Calculating the Verdet constant for the well-studied Terbium-Gallium-Garnet, we find that it accounts for  of the measured value at 800 mm.

The Verdet constants derived for the FE and IFE are found to be different, consistent with the breakdown of reciprocity between the two effects in the nonequilibrium ultrafast timescales as reported previously.

Our findings highlight the role of the optical magnetic field in the interaction between light and spins, in addition to the primary effects that stem from the electrical field."

New magnetic component discovered in the Faraday effect after nearly two centuries

Faraday effects emerging from the optical magnetic field (open access)

Fig. 4 FE stemming from the optical magnetic field.
(a) Schematic illustration of the steady dynamics induced by a CP CW optical beam in the presence of an external static field.
(b) Comparison between the calculated and the Verdet constants ... Empirical data adopted from Ref.