Tian Y C, Zhang W H, Li F S, Wu Y L, Wu Q, Sun F, Zhou G Y, Wang Lili, Ma Xucun, Xue Qi-Kun, Zhao Jimin
Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
State Key Laboratory for Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China.
Phys Rev Lett. 2016 Mar 11;116(10):107001. doi: 10.1103/PhysRevLett.116.107001. Epub 2016 Mar 8.
We report the time-resolved excited state ultrafast dynamics of single unit cell (1 UC) thick FeSe films on SrTiO_{3} (STO), with FeTe capping layers. By measuring the photoexcited quasiparticles' density and lifetime, we unambiguously identify a superconducting (SC) phase transition, with a transition temperature T_{c} of 68 (-5/+2) K and a SC gap of Δ(0)=20.2±1.5 meV. The obtained electron-phonon coupling strength λ is as large as 0.48, demonstrating the likely crucial role of electron-phonon coupling in the high temperature superconductivity of the 1 UC FeSe on STO systems. We further find a 0.05 THz coherent acoustic phonon branch in the capping layer, which provides an additional decay channel to the gluing bosons.
我们报道了在SrTiO₃（STO）上具有FeTe覆盖层的单胞（1 UC）厚FeSe薄膜的时间分辨激发态超快动力学。通过测量光激发准粒子的密度和寿命，我们明确确定了一个超导（SC）相变，其转变温度Tc为68（-5/+2）K，超导能隙Δ(0)=20.2±1.5 meV。所获得的电子-声子耦合强度λ高达0.48，这表明电子-声子耦合在STO体系上1 UC FeSe的高温超导中可能起着关键作用。我们还在覆盖层中发现了一个0.05 THz的相干声学声子分支，它为凝聚玻色子提供了一个额外的衰变通道。
