Superconductivity, charge- or spin-density wave, and metal-nonmetal transition in BaTi2(Sb1−xBix)2O

Hui-Fei Zhai; Wen-He Jiao; Yun-Lei Sun; Jin-Ke Bao; Hao Jiang; Xiao-Jun Yang; Zhang-Tu Tang; Qian Tao; Xiao-Feng Xu; Yu-Ke Li; Chao Cao; Jian-Hui Dai; Zhu-An Xu; Guang-Han Cao

doi:10.1103/PhysRevB.87.100502

Superconductivity, charge- or spin-density wave, and metal-nonmetal transition in BaTi2(Sb1−xBix)2O

Hui-Fei Zhai, Wen-He Jiao, Yun-Lei Sun, Jin-Ke Bao, Hao Jiang, Xiao-Jun Yang, Zhang-Tu Tang, Qian Tao, Xiao-Feng Xu, Yu-Ke Li, Chao Cao, Jian-Hui Dai, Zhu-An Xu, Guang-Han Cao

DOI 10.1103/PhysRevB.87.100502 · Physical Review B

T1

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Abstract

We have performed an isovalent substitution study in a layered titanium oxypnictide system BaTi2(Sb1−xBix)2O (0⩽x⩽0.40) by measurements of x-ray diffraction, electrical resistivity, and magnetic susceptibility. The parent compound BaTi2Sb2O is confirmed to exhibit superconductivity at 1.5 K as well as charge- or spin-density wave (CDW/SDW) ordering below 55 K. With the partial substitution of Sb by Bi, the lattice parameters a, c, and c/a all increase monotonically, indicating a negative chemical pressure and lattice distortion for the (super)conducting Ti2Sb2O layers. Bi doping elevates the superconducting transition temperature to its maximum Tc=3.7 K at x=0.17, and then Tc decreases gradually with further Bi doping. A metal-to-nonmetal transition takes place around x=0.3, and superconductivity at ∼1 K survives on the nonmetal side. The CDW/SDW anomaly, in comparison, is rapidly suppressed by Bi doping, and vanishes for x⩾0.17. The results are discussed in terms of negative chemical pressure and the disorder effect.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
BaTi2Sb2O Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	1.5	Pressure not reported	onset
BaTi2Sb2O Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	1.5	Pressure not reported	unknown
BaTi2(Sb1-xBix)2O Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	3.7	Pressure not reported	onset
BaTi2(Sb1-xBix)2O Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	3.7	Pressure not reported	unknown
BaTi2(Sb1-xBix)2O Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	0.8	Pressure not reported	unknown
Ba2Ti2Fe2As4O Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	21	Pressure not reported	unknown
BaTi2Bi2O Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	4.6	Pressure not reported	unknown