Interplay between antiferrodistortive, ferroelectric, and superconducting instabilities in Sr1-x Cax TiO3-δ

被引：27

作者：

de Lima, B. S. ^{[1
]}

da Luz, M. S. ^{[1
,2
]}

Oliveira, F. S. ^{[1
]}

Alves, L. M. S. ^{[1
]}

dos Santos, C. A. M. ^{[1
]}

Jomard, F. ^{[3
]}

Sidis, Y. ^{[4
]}

Bourges, P. ^{[4
]}

Harms, S. ^{[5
]}

Grams, C. P. ^{[5
]}

Hemberger, J. ^{[5
]}

Lin, X. ^{[6
]}

Fauque, B. ^{[6
]}

Behnia, K. ^{[6
]}

机构：

[1] Univ Sao Paulo, Escola Engn Lorena, Lorena, Brazil

[2] Univ Fed Triangulo Mineiro, Inst Ciencias Tecnol & Exatas, Uberaba, Brazil

[3] CNRS UVSQ, Grp Etud Matiere Condensee, F-78035 Versailles, France

[4] CEA CNRS, Lab Leon Brillouin, F-91191 Gif Sur Yvette, France

[5] Univ Cologne, Inst Phys 2, D-50937 Cologne, Germany

[6] CNRS ESPCI UPMC, Lab Phys & Etud Mat, F-75005 Paris, France

来源：

PHYSICAL REVIEW B | 2015年 / 91卷 / 04期

基金：

巴西圣保罗研究基金会;

关键词：

PHASE-TRANSITION; TEMPERATURE; SR1-XCAXTIO3; DEPENDENCE; SRTIO3;

D O I：

10.1103/PhysRevB.91.045108

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

SrTiO3 undergoes a cubic-to-tetragonal phase transition at 105 K. This antiferrodistortive transition is believed to be in competition with incipient ferroelectricity. Substituting strontium by isovalent calcium induces a ferroelectric order. Introducing mobile electrons to the system by chemical nonisovalent doping, on the other hand, leads to the emergence of a dilute metal with a superconducting ground state. The link between superconductivity and the other two instabilities is a question gathering momentum in the context of a popular paradigm linking unconventional superconductors and quantum critical points. We present a set of specific-heat, neutron-scattering, dielectric-permittivity, and polarization measurements on Sr1-x Ca-x TiO3 (0 < x < 0.009) and a study of low-temperature electric conductivity in Sr-0.9978 Ca-0.0022 TiO3-delta. Calcium substitution was found to enhance the transition temperature for both antiferrodistortive and ferroelectric transitions. Moreover, we find that Sr-0.9978 Ca-0.0022 TiO3-delta has a superconducting ground state. The critical temperature in this rare case of a superconductor with a ferroelectric parent is slightly lower than in SrTiO3-delta of comparable carrier concentration. A three-dimensional phase diagram for Sr1-x Ca-x TiO3-delta tracking the three transition temperatures as a function of x and delta results from this study, in which ferroelectric and superconducting ground states are not immediate neighbors.

引用

页数：9

共 48 条

[1] Conduction-band edge and Shubnikov-de Haas effect in low-electron-density SrTiO3 [J].