Anisotropic Thermopower of the Kondo Insulator $$\hbox {CeRu}_4\hbox {Sn}_6$$ CeRu 4 Sn 6

Abstract

The intermetallic compound CeRu 4 Sn 6 has been tentatively classified as Kondo insulator. This class of material, especially non-cubic representatives,is not yet fully understood. Here we report thermopower measurements on single-crystalline CeRu 4 Sn 6 between 2 K and 650 K, along the main crystallographic directions. Large positive thermopower is observed in the directions along which the hybridization is strong and a Kondo insulating gap forms. A negative contribution to the thermopower dominates for the crystallographic c axis where hybridization is weak and metallicity prevails.

Electronic structure of CeRu4Sn6: a density functional plus dynamical mean field theory study

“…This has been confirmed by density functional theory plus dynamical mean field theory (DFT+DMFT) 16,17 calculations of the optical conductivity 12 . Likewise the thermopower 13,18 , resistivity 19 and magnetic properties 15 are strongly anisotropic.…”

Pressure effect in the Kondo semimetal CeRu 4 Sn 6 with nontrivial topology

“…We note that a few published works on single crystalline CeRu 4 Sn 6 have employed samples grown from a floating zone furnace. [16,17] Polycrystalline samples of CeRu 4 (Sn 1−x Ge x ) 6 were also prepared by arc melting, with Sn partially substituted by Ge in order to achieve a chemical pressure. The foreign peaks as revealed in Fig.…”

Thermal conductivity of the Kondo semiconductor CeRu4Sn6

“…We calculated the electronic part of the thermal conductivity κ WF from the electrical resistivity ρ [13] employing the Wiedemann-Franz law κ WF = L 0 T /ρ with the Lorenz number L 0 = 2.44 × 10 −8 WΩK −2 . κ is essentially isotropic, in marked contrast to other physical properties such as electrical resistivity [13], thermopower [14], and optical conductivity [15].…”

“…It was first synthesized in 1992 [9] and a development of a narrow gap was found in several physical properties [10][11][12]. Measurements on single crystals revealed large anisotropy in resistivity, specific heat, and thermopower [12][13][14]. Optical conductivity measurements and LDA+DMFT calculations attributed this to a gapping in the tetragonal plane while the out-of-plane direction stays weakly metallic [15].…”