Structural and electrical characterization of the monolayer Kondo-lattice compound CePt$_6$/Pt(111)

TL;DR

This study investigates the growth, structure, and electronic properties of a monolayer CePt$_6$ on Pt(111), revealing a new surface compound and potential two-dimensional Kondo effects through advanced microscopy and spectroscopy techniques.

Contribution

It provides the first detailed structural and electronic characterization of a monolayer CePt$_6$ on Pt(111), including a structural model and insights into surface states and Kondo phenomena.

Findings

Formation of a new 1 u.l. CePt$_6$ surface compound with a $(2 imes 2)$ structure.

Observation of a shift in surface state energy below Fermi level due to charge transfer.

Evidence suggesting possible two-dimensional coherent Kondo effect.

Abstract

We report the growth process, structure, and electronic states of 1 unit layer (u.l.) of a Ce-Pt intermetallic compound on Pt(111) using scanning tunneling microscopy/spectroscopy (STM/STS) and low-energy electron diffraction. An ordered $(2 \times 2)$ structure was observed in the form of films or nanoislands depending on Ce dose by annealing at around 700 K. A structural model constructed from atomically resolved STM images and quasiparticle interference (QPI) patterns indicates the formation of a new surface compound 1 u.l. CePt$_6$ on Pt(111) terminated by a Pt layer. A lateral lattice constant of the 1 u.l. CePt$_6$ on Pt(111) is expanded from the value of a bulk CePt$_5$ crystal to match the Pt(111) substrate. By measuring d$I$/d$V$ spectra and QPI, we observed an onset energy of the surface state found on Pt(111) above Fermi energy ($E_F$) shifts below $E_F$ on the Pt layer of the 1 u.l. CePt$_6$ due to charge transfer from the underneath CePt$_2$ layer. We discuss a possible two-dimensional coherent Kondo effect with the observed spectra on the 1 u.l. CePt$_6$.