Polymorphic Kondo Effects Driven by Spin Lattice Coupling in VTe2

Abstract

Polymorphism in transition metal dichalcogenides (TMDs) allows unique physical properties to be controlled, such as artificial heavy fermion phenomena, the quantum spin Hall effect, and optimized device operations with 2D materials. Besides lattice structural and metal-semiconductor polymorphs, intriguing charge density wave (CDW) states with different electronic and magnetic phases are demonstrated in TMDs. Typically, the "normal" state is stabilized at high temperature above the CDW energy scale, and therefore, is not relevant to many low-temperature quantum phenomena, such as magnetic ordering and the heavy fermion Kondo state. Here, a local and robust phase manipulation of the normal (1T) and CDW (1T') states of VTe2 is reported by laser irradiation, and polymorphic Kondo effects are demonstrated with the two phases at low temperatures. The theoretical calculations show that Kondo screening of vanadium 3d electron moments is markedly enhanced in 1T'-VTe2, which is responsible for the observed transport properties distinct from its 1T counterpart. Controlling the spin-lattice coupling and Kondo physics via laser-driven CDW phase patterning allows the design of correlated electronic and magnetic properties in TMDs.