Charge transport in a polar metal
Charge transport in a polar metal
复制标题
DOI：
10.1038/s41535-019-0200-1
复制
发表时间：
2019-09
影响因子：
5.7
通讯作者：
Jialu Wang;Liangwei Yang;C. Rischau;Zhuokai Xu;Z. Ren;T. Lorenz;J. Hemberger;Xiao Lin;Kamran Behnia
中科院分区：
文献类型：
--
作者：
Jialu Wang;Liangwei Yang;C. Rischau;Zhuokai Xu;Z. Ren;T. Lorenz;J. Hemberger;Xiao Lin;Kamran Behnia
电偶极子在费米海中的命运是一个老问题，但很少探索。SrCaTiO在窄的（）取代窗口中具有稳定但稀的铁电性。这种绝缘体通过去除一小部分氧原子而变成金属。在这里，我们提出了一个详细的研究低温电荷输运SrCaTiO，记录电阻率随载流子浓度增加的演变（）。在阈值载流子浓度以下，极性结构相变具有明显的电阻率特征，并且Ca取代显著降低了给定载流子密度下的2 K迁移率。对于三种不同的Ca浓度，我们发现当大约个偶极子引入一个移动的电子时，相变消失。该阈值对应于由Ruderman-Kittel-Kasuya-Yosida（RKKY）相互作用的双极性对应物介导的反铁电耦合中的预期峰值。我们的结果表明，即使在存在稀释费米海的情况下，跃迁也是由偶极-偶极相互作用驱动的。电荷输运表现出非单调的温度依赖性，最有可能是由散射的横向光学声子模式。这种极性金属中电荷传输的定量解释仍然是对理论的挑战。对于，电阻率遵循T平方行为以及轻微的上升（在无钙和钙取代的样品）。后者使人想起近藤效应，最有可能是由于氧空位。
The fate of electric dipoles inside a Fermi sea is an old issue, yet poorly explored. SrCaTiOhosts a robust but dilute ferroelectricity in a narrow () window of substitution. This insulator becomes metallic by removal of a tiny fraction of its oxygen atoms. Here, we present a detailed study of low-temperature charge transport in SrCaTiO, documenting the evolution of resistivity with increasing carrier concentration (). Below a threshold carrier concentration,, the polar structural-phase transition has a clear signature in resistivity and Ca substitution significantly reduces the 2 K mobility at a given carrier density. For three different Ca concentrations, we find that the phase transition fades away when one mobile electron is introduced for aboutdipoles. This threshold corresponds to the expected peak in anti-ferroelectric coupling mediated by a diplolar counterpart of Ruderman–Kittel–Kasuya–Yosida (RKKY) interaction. Our results imply that the transition is driven by dipole–dipole interaction, even in presence of a dilute Fermi sea. Charge transport forshows a non-monotonic temperature dependence, most probably caused by scattering off the transverse optical phonon mode. A quantitative explanation of charge transport in this polar metal remains a challenge to theory. For, resistivity follows a T-square behavior together with slight upturns (in both Ca-free and Ca-substituted samples). The latter are reminiscent of Kondo effect and most probably due to oxygen vacancies.