论文标题
通过碱金属吸附在SMS中的表面价转变
Surface valence transition in SmS by alkali metal adsorption
论文作者
论文摘要
使用基于同步加速器的核心级光电光谱和角度分辨光电光谱（ARPES）阐明钾（K）掺杂下SMS表面的电子结构变化。 SM核级和ARPES光谱表明，表面的SM平均价从几乎二价状态增加到三价状态，随着k沉积的增加。载体引起的价值过渡（CIVT）从SM $^{2+} $到SM $^{3+} $表现出与传统电子掺杂相反的行为。多余的电子被孤立的激子捕获，这与从压力下的黑色绝缘子的相过渡到带有SM $^{3+} $的金属的相位过渡。该CIVT有助于阐明该材料中压力引起的黑色至金质相变，该材料源自激子的Mott过渡。
The electronic structure changes of SmS surfaces under potassium (K) doping are elucidated using synchrotron-based core-level photoelectron spectroscopy and angle-resolved photoelectron spectroscopy (ARPES). The Sm core-level and ARPES spectra indicate that the Sm mean valence of the surface increased from the nearly divalent to trivalent states, with increasing K deposition. Carrier-induced valence transition (CIVT) from Sm$^{2+}$ to Sm$^{3+}$ exhibits a behavior opposite to that under conventional electron doping. Excess electrons are trapped by isolated excitons, which is inconsistent with the phase transition from the black insulator with Sm$^{2+}$ to the gold metal with Sm$^{3+}$ under pressure. This CIVT helps to clarify the pressure-induced black-to-golden phase transition in this material, which originates from the Mott transition of excitons.
