Nanoscale Manipulation of the Local Kondo Effect in an Artificial Heavy-Fermion System.

Abstract

Two-dimensional (2D) van der Waals heterostructures based on <i>d</i>-electron materials offer a platform for realizing heavy-Fermion systems with Kondo lattices. However, the nondestructive and reversible manipulation of spins at the nanoscale in 2D heavy-Fermion materials─essential for their application in spintronic devices─remains elusive. In this paper, we successfully manipulate and characterize both spin (Kondo effects) and electronic (charge density wave) degrees of freedom in the 2D heavy-Fermion system of 1T/1H-TaSe₂ heterostructure using scanning tunneling microscopy/spectroscopy (STM/STS). By applying voltage pulses, we precisely control the chirality and arrangement of the charge density wave coupled with local spins in 1T-TaSe₂. This process also leads to the generation and annihilation of two distinct types of domain walls (DWs). Combining STS and first-principles calculations, we reveal that the local spins are quenched in the type-II DW, which forms between two domains exhibiting a phase shift yet possessing identical chirality. This results in the disappearance of the Kondo resonance. The Mott phase also quenches within type-II DWs. Our results demonstrate a nondestructive and reversible approach to manipulate and understand the local spins of the Kondo lattice in artificial 2D heavy-Fermion systems with nanoscale precision.