Critical Doping for the Onset of a Two-Band Superconducting Ground State in SrTiO3-δ
Critical Doping for the Onset of a Two-Band Superconducting Ground State in SrTiO3-δ
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DOI：
10.1103/physrevlett.112.207002
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发表时间：
2014-05-21
影响因子：
8.6
通讯作者：
Behnia, Kamran
中科院分区：
文献类型：
--
作者：
Lin, Xiao;Bridoux, German;Behnia, Kamran
在掺杂SrTiO 3超导性持续下降到一个非常低的浓度的移动的电子。这限制了相关的能量窗口和可能的配对场景。我们研究了载流子密度从10（17）cm ~（-3）到10（20）cm ~（-3）的量子振荡和超导转变温度Tc，并确定了对应于上带填充阈值的两个临界掺杂水平。在第一个临界掺杂，分离的单带和双带超导制度在缺氧样品，稳定增加的载流子浓度的Tc突然停止。在该掺杂水平附近，最低能带中的能量分散显示出从抛物线行为的向下偏离。结果施加新的约束微观配对的情况下。
In doped SrTiO3 superconductivity persists down to an exceptionally low concentration of mobile electrons. This restricts the relevant energy window and possible pairing scenarios. We present a study of quantum oscillations and superconducting transition temperature T-c as the carrier density is tuned from 10(17) to 10(20) cm(-3) and identify two critical doping levels corresponding to the filling thresholds of the upper bands. At the first critical doping, which separates the single-band and the two-band superconducting regimes in oxygen-deficient samples, the steady increase of T-c with carrier concentration suddenly stops. Near this doping level, the energy dispersion in the lowest band displays a downward deviation from parabolic behavior. The results impose new constraints for microscopic pairing scenarios.