Doping Effects on the Electronic Structure of an Anisotropic Kondo Semiconductor CeOs${}_2$Al${}_{10}$: An Optical Study with Re and Ir Substitution

Abstract

An anisotropic Kondo semiconductor CeOs${}_2$Al${}_{10}$ exhibits an unusual antiferromagnetic order at rather high transition temperature $T_0$ of 28.5 K. Two possible origins of the magnetic order have been proposed so far, one is the Kondo coupling of the hybridization between the conduction ($c$) and the $4f$ states and the other is the charge-density wave/charge ordering along the orthorhombic $b$ axis. To clarify the origin of the magnetic order, we have investigated the electronic structure of hole- and electron-doped CeOs${}_2$Al${}_{10}$ [Ce(Os${}_{1-y}$Re${}_y$)${}_2$Al${}_{10}$ and Ce(Os${}_{1-x}$Ir${}_x$)${}_2$Al${}_{10}$, respectively] by using optical conductivity spectra along the $b$ axis. The intensity of the $c$-$f$ hybridization gap at $\hslash \omega \sim 50$ meV continuously decreases from $y=0.10$ to $x=0.12$ via $x=y=0$. The intensity of the charge excitation observed at $\hslash \omega \sim 20$ meV has the maximum at $x=y=0$ as similar with the doping dependence of $T_0$. The fact that the charge excitation is strongly related to the magnetic order strengthens the possibility of the charge density wave/charge ordering as the origin of the magnetic order.

5 pages, 3 figures, to be published in J. Phys. Soc. Jpn

References in corpus (3)

• Origin of Middle-Infrared Peaks in Cerium Compounds
• Optical Evidence of Itinerant-Localized Crossover of $4f$ Electrons in Cerium Compounds
• Relation between $c$-$f$ hybridization and magnetic ordering in CeRu${}_2$Al${}_{10}$: An optical conductivity study of Ce(Ru${}_{1-x}$Rh${}_x$)${}_2$Al${}_{10}$ ($x\le 0.05$)