Topological Fermi-arc surface state covered by floating electrons on a two-dimensional electride

Chan-young Lim; Min-Seok Kim; Dong Cheol Lim; Sunghun Kim; Yeonghoon Lee; Jaehoon Cha; Gyubin Lee; Sang Yong Song; Dinesh Thapa; Jonathan D. Denlinger; Seong-Gon Kim; Sung Wng Kim; Jungpil Seo; Yeongkwan Kim

doi:10.1038/s41467-024-49841-6

paper

Topological Fermi-arc surface state covered by floating electrons on a two-dimensional electride

arXiv:2407.09153 · doi:10.1038/s41467-024-49841-6

Abstract

Two-dimensional electrides can acquire topologically non-trivial phases due to intriguing interplay between the cationic atomic layers and anionic electron layers. However, experimental evidence of topological surface states has yet to be verified. Here, via angle-resolved photoemission spectroscopy (ARPES) and scanning tunnelling microscopy (STM), we probe the magnetic Weyl states of the ferromagnetic electride $[G d_{2}$ C]^{2+}\cdot2e^{-} $. I n p a r t i c u l a r, t h e p r ese n ceo f W ey l co n es an d F er mi - a r cs t a t es i s d e m o n s t r a t e d t h r o ug h p h o t o n e n er g y - d e p e n d e n t A R P E S m e a s u r e m e n t s, a g r ee in g w i t h t h eor e t i c a l ban d s t r u c t u r ec a l c u l a t i o n s . N o t ab l y, t h e S T M m e a s u r e m e n t sr e v e a l t ha tt h e F er mi - a r cs t a t ese x i s t u n d er n e a t ha f l o a t in g q u an t u m e l ec t r o n l i q u i d o n t h e t o pG d l a y er, f or min g d o u b l e - s t a c k e d s u r f a ces t a t es inah e t er os t r u c t u r e . O u r w or k t h u s n o t o n l y u n v e i l s t h e n o n - t r i v ia l t o p o l o g y o f t h e$ [Gd_{2} $C]^{2 +} \cdot 2 e^{-}$ electride but also realizes a surface heterostructure that can host phenomena distinct from the bulk.

22 pages, 6 figures