Structural and Electronic Interplay in the Gap Formation in CeRhAs_<1-x>Sb_x (0 ≤ x ≤ 1)(Condensed Matter : Electronic Structure, Electrical, Magnetic and Optical Properties)

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Both CeRhAs and CeRhSb are known to open a narrow pseudogap at the Fermi level. For the alloys CeRhAs_<1-x>Sb_x (0 $le; x $le; 1), we report the magnetic, transport and x-ray diffraction measurements. For x = 0, the orthorhombic ε-TiNiSi-type crystal structure with a 2b x 2c superlattice changes to the hexagonal LiGaGe-type upon heating above 360K, thereby the Ce chain is straightened. The phase transitions disappear upon alloying at a small level x = 0.025, and alloys for 0.25 $le; x $le; 0.50 adopt the hexagonal YPtAs-type structure at room temperature. Over the wide range 0.025 $le; x $le; 0.94, no clear sign of gap is observed in either magnetic susceptibility, specific heat, resistivity or thermopower. The electronic specific heat coefficients for the end compounds at x = 0 and x = 1 are ten-fold increased by alloying at x = 0.025 and x = 0.94, respectively. These results indicate that not only the coherent hybridization of the 4f wave function with the conduction bands in the e-TiNiSi-type structure but also the superlattice structure play important roles in the gap formation in CeRhAs.
社団法人日本物理学会の論文
2004-01-15