Anomalous Transport Properties in BiS2-based Superconductors LnO1−xFxBiS2 (Ln = Nd, La-Sm)

• Published in: Journal of the Physical Society of Japan 2019-02, Vol.88 (4), p.1
• Main Authors: Iwasaki, Sho, Kawai, Yoshiki, Takahashi, Shotaro, Suda, Takaya, Wang, Ying, Koshino, Yasunori, Ogura, Fumiya, Shibayama, Yoshiyuki, Kurosawa, Tohru, Oda, Migaku, Ido, Masayuki, Momono, Naoki
• Format: Article
• Language: English
• Subjects: Bismuth; Charge density waves; Electronic properties; Energy gap; Fermi surfaces; Hall effect; Lattice instability; Transport properties; X-ray diffraction
• ISSN: 0031-9015; 1347-4073
• DOI: 10.7566/JPSJ.88.041005

We report the electronic properties of the layered bismuth-based sulfide superconductors NdO1−xFxBiS2 (x = 0.25, 0.4, and 0.5) and La1−ySmyO0.5F0.5BiS2 (y = 0.1–0.7), which have been studied by investigation of their transport properties and X-ray diffraction. In the lightly carrier-doped NdO1−xFxBiS2 (x = 0.25 and 0.4) and La1−ySmyO0.5F0.5BiS2 (y = 0.3 and 0.4), the resistivity and Hall coefficient exhibit anomalous temperature dependences below TCDW ∼ 130 and 200 K, respectively, suggesting the formation of an energy gap on the Fermi surface associated with charge-density wave (CDW). In NdO1−xFxBiS2 (x = 0.25), the bond angles and bond lengths of the Bi–S pentahedron change their temperature dependences below ∼200 K, suggesting that a lattice instability related to the Bi–S pentahedron exists below ∼200 K, which is much higher than TCDW. These results indicate that the lattice instability of the Bi–S pentahedron can trigger a CDW transition in the low-carrier region of BiS2 superconductors.