Optical spectroscopy study on the electronic structure of $E{u}_{1-x}C{a}_x{B}_6$

Abstract

The optical conductivity ${\sigma }_1(\omega )$ of Eu${}_{1-x}$Ca${}_x$B${}_6$ has been obtained from reflectivity and ellipsometry measurements for series of compositions, $0\le x\le 1$. The interband part of ${\sigma }_1(\omega )$ shifts continuously to higher frequency as Ca-content $x$ increases. Also the intraband spectral weight of ${\sigma }_1(\omega )$ decreases rapidly and essentially vanishes for $x\ge x_c=0.35$. These results show that the valence band and the conduction band of Eu${}_{1-x}$Ca${}_x$B${}_6$ move away from each other such that their band overlap decreases with increasing Ca-substitution. As a result, the electronic state evolves from the semimetallic structure of EuB${}_6$ to the insulating CaB${}_6$ where the two bands are separated to open a finite gap ($\simeq 0.25$ eV) at the X-point of the Brillouin zone.

arXiv comment5 pages, 4 figures

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• Theory of Excitonic States in CaB6
• Magneto-optical Kerr effect in $E{u}_{1-x}C{a}_x{B}_6$

Cited by in corpus (5)

• Electrodynamics of Correlated Electron Materials
• Electronic Structure Calculations with the Tran-Blaha Modified Becke-Johnson Density Functional
• Electronic properties of EuB6 in the ferromagnetic regime: Half-metal versus semiconductor
• From bad metal to Kondo insulator: temperature evolution of the optical properties of SmB${}_6$
• Semimetallic Nature and Magnetic Polarons in EuB6 Studied by Angle-Resolved Photoemission Spectroscopy