Baldini E, Mann A, Benfatto L, Cappelluti E, Acocella A, Silkin V M, Eremeev S V, Kuzmenko A B, Borroni S, Tan T, Xi X X, Zerbetto F, Merlin R, Carbone F
Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
Phys Rev Lett. 2017 Sep 1;119(9):097002. doi: 10.1103/PhysRevLett.119.097002. Epub 2017 Aug 31.
In systems having an anisotropic electronic structure, such as the layered materials graphite, graphene, and cuprates, impulsive light excitation can coherently stimulate specific bosonic modes, with exotic consequences for the emergent electronic properties. Here we show that the population of E_{2g} phonons in the multiband superconductor MgB_{2} can be selectively enhanced by femtosecond laser pulses, leading to a transient control of the number of carriers in the σ-electronic subsystem. The nonequilibrium evolution of the material optical constants is followed in the spectral region sensitive to both the a- and c-axis plasma frequencies and modeled theoretically, revealing the details of the σ-π interband scattering mechanism in MgB_{2}.
在具有各向异性电子结构的体系中，例如层状材料石墨、石墨烯和铜酸盐，脉冲光激发能够相干地激发特定的玻色子模式，从而对所呈现的电子性质产生奇特的影响。在此我们表明，飞秒激光脉冲能够选择性地增强多带超导体MgB₂中E₂g声子的布居数，进而实现对σ电子子系统中载流子数量的瞬态控制。在对a轴和c轴等离子体频率均敏感的光谱区域中跟踪材料光学常数的非平衡演化，并进行理论建模，揭示了MgB₂中σ-π带间散射机制的细节。
