论文标题
SMS中的照片诱导的非线性带移位和价值转变
Photo-induced nonlinear band shift and valence transition in SmS
论文作者
论文摘要
使用高谐波生成激光时间分辨的光电部光谱研究，研究了基于稀土的半导体单硫化物（SMS）的光诱导的带结构变化。观察到了SM 4F多重组的非线性光诱导的带轮移位。第一个是由于大约93 meV的较大的表面光伏（SPV）效应，与散装带隙的大小相当，放松时间比0.1 ms更长，因此向高结合能量侧移动。第二个是超快带向低结合能侧的移位，该方向与SPV偏移相反，这表明由于光兴趣而导致的超快价从二价到三价到三价SM离子。后者的能量转移约为58 meV，这与从环境压力到黑色绝缘体和金属相之间的边界的能量间隙转移一致。这表明光诱导的价值过渡可以达到相边界，但是其他效果对于实现金属相是必要的。
The photo-induced band structure variation of a rare-earth-based semiconductor, samarium monosulfide (SmS), was investigated using high-harmonic-generation laser-based time-resolved photoelectron spectroscopy. A nonlinear photo-induced band shift of the Sm 4f multiplets was observed. The first one is a shift to the high-binding-energy side due to a large surface photovoltage (SPV) effect of approximately 93 meV, comparable to the size of the bulk band gap, with a much longer relaxation time than 0.1 ms. The second one is an ultrafast band shift to the low binding energy side, which is in the opposite direction to the SPV shift, suggesting an ultrafast valence transition from divalent to trivalent Sm ions due to photo-excitation. The latter energy shift was approximately 58 meV, which is consistent with the energy gap shift from ambient pressure to the boundary between the black insulator and golden metallic phase with the application of pressure. This suggests that the photo-induced valence transition can reach the phase boundary, but other effects are necessary to realize the golden metallic phase.
