Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York 11973, USA.
Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA.
Phys Rev Lett. 2018 Dec 7;121(23):236802. doi: 10.1103/PhysRevLett.121.236802.
We report the observation of multiple phonon satellite features in ultrathin superlattices of the form nSrIrO_{3}/mSrTiO_{3} using resonant inelastic x-ray scattering (RIXS). As the values of n and m vary, the energy loss spectra show a systematic evolution in the relative intensity of the phonon satellites. Using a closed-form solution for the RIXS cross section, we extract the variation in the electron-phonon coupling strength as a function of n and m. Combined with the negligible carrier doping into the SrTiO_{3} layers, these results indicate that the tuning of the electron-phonon coupling can be effectively decoupled from doping. This work both showcases a feasible method to extract the electron-phonon coupling in superlattices and unveils a potential route for tuning this coupling, which is often associated with superconductivity in SrTiO_{3}-based systems.
我们通过共振非弹性 X 射线散射（RIXS）观察到了 nSrIrO_{3}/mSrTiO_{3} 形式的超薄超晶格中多个声子卫星特征。随着 n 和 m 值的变化，能量损失谱中声子卫星的相对强度表现出系统的演化。通过对 RIXS 截面的闭式解，我们提取了电子-声子耦合强度随 n 和 m 的变化。结合 SrTiO_{3} 层中可忽略的载流子掺杂，这些结果表明可以有效地将电子-声子耦合的调谐与掺杂分离。这项工作既展示了一种从超晶格中提取电子-声子耦合的可行方法，也揭示了一种可能的调谐这种耦合的途径，这种耦合通常与 SrTiO_{3} 基体系中的超导性有关。
