Surface valence transition in SmS by alkali metal adsorption
Surface valence transition in SmS by alkali metal adsorption
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DOI：
10.1103/physrevb.107.l041102
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发表时间：
2022-05
影响因子：
3.7
通讯作者：
Takuto Nakamura;T. Nakaya;Y. Ohtsubo;Hiroki Sugihara;Kiyohisa Tanaka;R. Yukawa;M. Kitamura;H. Kumigashira;K. Imura;H. Suzuki;N. Sato;S. Kimura
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文献类型：
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作者：
Takuto Nakamura;T. Nakaya;Y. Ohtsubo;Hiroki Sugihara;Kiyohisa Tanaka;R. Yukawa;M. Kitamura;H. Kumigashira;K. Imura;H. Suzuki;N. Sato;S. Kimura
利用同步加速器的核能级光电子能谱和角分辨光电子能谱（ARPES）分析了钾(K)掺杂下SmS表面的电子结构变化。Sm核能级和ARPES谱表明，随着K沉积的增加，表面Sm均价从近二价态增加到三价态。从sm2 +到sm3 +的载流子诱导价跃迁（CIVT）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，这与在压力下从含sm2 +的黑色绝缘体到含sm3 +的金金属的相变不一致。该CIVT有助于阐明该材料中由激子莫特跃迁引起的压力诱导的黑到金相变。
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.