Unusual upper critical field behavior in Nb-doped bismuth selenides

Kaya Kobayashi, T. Ueno, H. Fujiwara, T. Yokoya, J. Akimitsu


29 被引用数 (Scopus)


We investigate superconductivity in the candidate topological superconductor NbxBi2Se3 from x=0 to 1. We observe superconductivity for all x>0 with a superconducting transition temperature TC∼ 3 K similar to that reported in Cu- and Sr-intercalated Bi2Se3. Structurally, for small x we find introduction of Nb modifies the Bi2Se3 separation while for larger x the system is driven to the BiSe structure. While all compounds are found to be superconducting, two distinct behaviors for the upper critical field Hc2 are observed. From photoemission spectroscopy we find that the enhanced Hc2 corresponds to compounds with a low surface Dirac point energy (-0.67 eV) relative to the Fermi level; in absolute scale this value is lower than previously reported superconductors in this materials family. We comment on the utility of this system for the study of topological superconductivity in a new structure type combining a doping (Bi2 type) layer and layers with topologically protected gapless state (Bi2Se3 type).

ジャーナルPhysical Review B
出版ステータスPublished - 5月 16 2017

ASJC Scopus subject areas

  • 電子材料、光学材料、および磁性材料
  • 凝縮系物理学


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