‧제목 Electronic properties of anionic electrons in two-dimensionalY2C Electrides
‧연사 세종대학교 물리천문학과 김건 교수님
‧일시 2018년 3월 21일 (수요일) 오후 5시
‧장소 영실관 601호
초 록
Electrides are ionic compounds, in which electrons confined in the interstitial spaces serve as anions, and are attractive owing to their exotic physical and chemical properties in terms of their low work function and efficient charge transfer characteristics related to chemical reactions. Depending on the topology of anionic electrons, the surface electronic structures of electrides can be significantly altered, which, in turn, impacts their properties. In particular, the atomic and electronic structures of two-dimensional (2D) electride surfaces are of interest, because the localized anionic electrons at the interlayer space can be naturally exposed to cleaved surfaces. In this work, we report the atomic and local electronic structure of the Y2C electride surface, using scanning tunneling microscopy and first-principles calculations, revealing that anionic electrons at cleaved surface are absorbed into the surface and subsequently resurged onto the surface by an electric field. It is highlighted that the estranged anionic electrons from the biased surface occupy the slightly shifted crystallographic site compared to the bulk Y2C electride. These results demonstrate that the partially delocalized electrons at electride surfaces can be regarded as a 2D electron gas. The measured density of states around the Fermi level and work function reveal that the 2D electronic state at the cleaved surface of Y2Cis dominated by the localized anionic electrons.
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