Extraction of magnetic circular dichroism effects from blended mixture of magnetic linear dichroism signals in the cobalt/Scotch tape system

Chien-Hua Huang,Hua-Shu Hsu,Lech Tomasz Baczewski,Shih-Jye Sun,Paweł Misiuna,Yu-Ying Chang

doi:10.1038/s41598-019-53880-1

Abstract

Circular dichroism (CD) signals revealed in some materials may arise from different origins during measurements. Magnetic field dependent CD (MCD) emanating from the spin-polarized band provides direct insight into the spin–spin interband transitions in magnetic materials. On the contrary, natural CD effects which are artefactual signals resulting from the linear polarization (LP) components during the polarization modulation with a photo-elastic modulator in anisotropic polymer systems were usually observed. There is no simple method to reliably distinguish MCD effect due to spin polarized band structures from natural CD effect, which limits our understanding of the magnetic material/polymer hybrid structures. This paper aims to introduce a general strategy of averaging out the magnetic linear dichroism (MLD) contributions due to the anisotropic structure and disentangling MCD signal(s) from natural MCD signal(s). We demonstrate the effectiveness of separating MCD from natural MCD using rotational MCD measurement and presented the results of a sample with Co thin film on polymer Scotch tape (unplasticized polyvinyl chloride) glued on a quartz substrate. We demonstrate that the proposed method can be used as an effective tool in disentangling MCD and natural MCD effects, and it opens prospects to study the magnetic material /polymer hybrid systems.

Highlights

Magneto-optics is a useful method to detect electronic structures in magnetic and nonmagnetic materials
The signal intensities of CB and Circular dichroism (CD) involving an optical response to circular polarization are usually two or three orders of magnitude smaller when compared with those of linear birefringence (LB) and linear dichroism (LD) which originate in the anisotropy of materials against linear polarization[31,34,35]
We show the results of Magnetic field dependent CD (MCD) measurements on the sample composed of 50 nm thick polycrystalline Co thin film deposited on polymer Scotch tape glued on quartz substrate

Summary

Introduction

Magneto-optics is a useful method to detect electronic structures in magnetic and nonmagnetic materials. In the field of solid-state physics, MCD can be used to determine the absorption difference between spin channels to resolve the polarized valence states in magnetic materials[9,10,11,12,13,14,15,16,17]. This technique is sensitive to the polarized electronic states near the band edge. It is confirmed that the proposed rotational MCD method is efficient in the extraction of MCD effects from blended mixture of magnetic LD (MLD) signals in the cobalt/Scotch tape system

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Results

Conclusion