Visualization of Ce atoms and surface-induced magnetism in CeCoIn$_{5}$
ORAL
Abstract
CeCoIn$_{5}$ is known as a heavy fermion compound naturally born at the quantum critical point having an unconventional d-wave superconducting phase at low temperatures. Recently, several STM works on a cleaved surface of this compound reported visualization of emerging heavy fermion bands and consistency of the bulk superconducting properties reported previously. However, reported STM images in those works only visualized In atoms on the Ce-In plane even though the Ce-In plane contains Ce and In atoms. By performing precise low-temperature STM measurements on CeCoIn$_{5}$, we successfully visualize Ce atoms on the Ce-In plane and, in addition, surface-induced staggered dumbblell-shaped order on the Co plane. This ordered structure locally has C$_{2v}$ symmetry but retaining C$_{4}$ symmetry. This structure coexists with the superconductivity, and is robust against temperatures (\textgreater T$_{c})$ and an external magnetic field (\textgreater H$_{c2})$. In the talk, we will discuss the origin of the peculiar ordered structure based on our experimental observations together with first principles calculations.
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