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$_{10}$ ($x\leq0.05$)

Shin-ichi Kimura; Hiroshi Tanida; Masafumi Sera; Yuji Muro; Toshiro Takabatake; Takashi Nishioka; Masahiro Matsumura; Riki Kobayashi

doi:10.1103/PhysRevB.91.241120

paper

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 $_{10}$ ( $x \leq 0.05$ )

arXiv:1506.04494 · doi:10.1103/PhysRevB.91.241120

Abstract

A Kondo semiconductor CeRu $_{2}$ Al $_{10}$ with an orthorhombic crystal structure shows an unusual antiferromagnetic ordering at rather high temperature $T_{0}$ of 27.3 K, which is lower than the Kondo temperature $T_{K} \sim$ 60 K. In optical conductivity [ $σ (ω)$ ] spectra that directly reflect electronic structure, the $c$ - $f$ hybridization gap between the conduction and $4 f$ states is observed at around 40 meV along the three principal axes. However, an additional peak at around 20 meV appears only along the $b$ axis. With increasing $x$ to 0.05 in Ce(Ru $_{1 - x}$ Rh $_{x}$ ) $_{2}$ Al $_{10}$ , the $T_{0}$ decreases slightly from 27.3 K to 24 K, but the direction of the magnetic moment changes from the $c$ axis to the $a$ axis. Thereby, the $c$ - $f$ hybridization gap in the $σ (ω)$ spectra is strongly suppressed, but the intensity of the 20-meV peak remains as strong as for $x = 0$ . These results suggest that the change of the magnetic moment direction originates from the decreasing of the $c$ - $f$ hybridization intensity. The magnetic ordering temperature $T_{0}$ is not directly related to the $c$ - $f$ hybridization but is related to the charge excitation at 20 meV observed along the $b$ axis.

arXiv comment5+2 pages, 4+2 figures

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 $_{10}$ ( $x \leq 0.05$ )

Abstract

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Relation between c-f hybridization and magnetic ordering in CeRu2​Al10​: An optical conductivity study of Ce(Ru1−x​Rhx​)2​Al10​ (x≤0.05)

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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 $_{10}$ ( $x \leq 0.05$ )