Ferroelectric order versus metallicity in Sr1-xCaxTiO3-delta (x=0.009)

Article

关键词: ANTIFERROELECTRIC PHASE-TRANSITION;    SOFT PHONON MODES;    X-RAY;    RAMAN-SCATTERING;    STRONTIUM;    SRTIO3;    (SR1-XCAX)TIO3;    DIFFRACTION;    RESONANCE;    TRANSPORT;   

DOI  :  10.1103/PhysRevB.100.195121

来源: SCIE

【 摘 要 】

We report on a thermal-expansion study of the ferroelectric phase transition in insulating Sr1-xCaxTiO3 (x = 0.009) and its evolution upon increasing charge-carrier concentration up to n similar or equal to 60 x 10(19) cm(-3). Although electric polarization is screened by mobile charge carriers, we find clear signatures of the ferroelectric phase transition in the thermal-expansion coefficient alpha of the weakly doped metallic samples. Upon increasing n, the transition temperature T-C(n) and the magnitude of the anomalies in alpha rapidly decrease up to a threshold carrier density n* above which broadened anomalies remain present. There is no indication for a sign change of alpha as is expected for a pressure-dependent quantum phase transition with n as the control parameter. Thus, the ferroelectric like transition is either continuously fading away or it transforms to another low-temperature phase above n*, but this change hardly affects the temperature-dependent alpha(T) data.

【 授权许可】

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