Tc enhancement by aliovalent anionic substitution in superconducting BaTi2(Sb1-xSnx)2O

Year: 2013 DOI: 10.7566/JPSJ.82.074707

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Kousuke Nakano, Takeshi Yajima, Fumitaka Takeiri, Mark A. Green, James Hester, Yoji Kobayashi, Hiroshi Kageyama.   Journal of the Physical Society of Japan, 2013, 82, 074707/1-5.


BaTi2Sb2O is a Tc=1.2 K superconductor with a d1 square lattice, and isovalent Bi substitution for Sb can increase its Tc to 4.6 K (BaTi2Bi2O), accompanied by the complete suppression of charge density wave (CDW) or spin density wave (SDW) transition. In the present study, we demonstrate that aliovalent Sn substitution (hole doping) also increases Tc up to 2.5 K for BaTi2(Sb0.7Sn0.3)2O, while suppressing CDW/SDW transition only slightly. The overall electronic phase diagram of BaTi2(Sb,Sn)2O is qualitatively similar to that of cation-substituted (hole-doped) (Ba,Na)Ti2Sb2O, but quantitative differences such as in Tc are observed, which is discussed in terms of Ti–Pn hybridization and chemical disorder. ©2013 The Physical Society of Japan