Negative experimental evidence for magneto-orbital dichroism - supplemental information

TL;DR

This study conducted experiments to detect magnetic orbital dichroism (MOD) in chiral matter but found no significant evidence, suggesting that MOD is either very weak or nonexistent under the tested conditions.

Contribution

The paper provides experimental evidence that magnetic orbital dichroism is not observed at detectable levels, supporting the idea that it is negligible compared to magnetic circular dichroism.

Findings

MOD is smaller than 10^{-4} of MCD for the tested transition

Electric quadrupole interaction may be the lowest order mechanism for MOD

No significant MOD detected under the experimental conditions

Abstract

A light beam can carry both spin angular momentum (SAM) and orbital angular momentum (OAM). SAM is commonly evidenced by circular dichroism (CD) experiments {\em i. e.} differential absorption of left and right-handed circularly polarized light. Recent experiments, supported by theoretical work, indicate that the corresponding effect with OAM instead of SAM is not observed in chiral matter. Isotropic materials can show CD when subjected to a magnetic field (MCD). In Ref. ~\onlinecite{Mathevet2012} we report a set of experiments, under well defined conditions, searching for magnetic orbital dichroism (MOD), differential absorption of light as a function of the sign of its OAM. We experimentally demonstrate that this effect, if any, is smaller than a few $10^{-4}$ of MCD for the Nd:YAG $^4I_{9/2}\rightarrow^4F_{5/2}$ transition. This transition is essentially of electric dipole nature. We give an intuitive argument suggesting that the lowest order of light matter interaction leading to MOD is the electric quadrupole term. We give here more experimental details and extra measurements.