Nontrivial doping evolution of electronic properties in Ising-superconducting alloys

Abstract

Transition metal dichalcogenides offer unprecedented versatility to engineer 2D materials with tailored properties to explore novel structural and electronic phase transitions. In this work, we present the atomic-scale evolution of the electronic ground state of a monolayer of Nb${}_{1-\delta }$Mo${}_{\delta }$Se${}_2$ across the entire alloy composition range (0 < $\delta$ < 1) using low-temperature (300 mK) scanning tunneling microscopy and spectroscopy (STM/STS). In particular, we investigate the atomic and electronic structure of this 2D alloy throughout the metal to semiconductor transition (monolayer NbSe${}_2$ to MoSe${}_2$). Our measurements let us extract the effective doping of Mo atoms, the bandgap evolution and the band shifts, which are monotonic with $\delta$. Furthermore, we demonstrate that collective electronic phases (charge density wave and superconductivity) are remarkably robust against disorder. We further show that the superconducting TC changes non-monotonically with doping. This contrasting behavior in the normal and superconducting state is explained using first-principles calculations. We show that Mo doping decreases the density of states at the Fermi level and the magnitude of pair-breaking spin fluctuations as a function of Mo content. Our results paint a detailed picture of the electronic structure evolution in 2D TMD alloys, which is of utmost relevance for future 2D materials design.

References in corpus (19)

• Observation of giant bandgap renormalization and excitonic effects in a monolayer transition metal dichalcogenide semiconductor
• Evidence of Ising pairing in superconducting NbSe${}_2$ atomic layers
• Realization of Quantum Spin Hall State in Monolayer 1T'-WTe2
• Characterization of collective ground states in single-layer NbSe2
• Edge conduction in monolayer WTe2
• Quality heterostructures from two dimensional crystals unstable in air by their assembly in inert atmosphere
• Observation of charge density wave order in 1D mirror twin boundaries of single-layer MoSe2
• Spin-orbit engineering in transition metal dichalcogenide alloy monolayers
• Imaging spinon density modulations in a 2D quantum spin liquid
• Tunable Doping of Rhenium and Vanadium into Transition Metal Dichalcogenides for Two-Dimensional Electronics
• Disorder induced multifractal superconductivity in monolayer niobium dichalcogenides
• Absence of ferromagnetism in VSe${}_2$ caused by its charge density wave phase
• Modulating Electronic Structure of Monolayer Transition Metal Dichalcogenides by Substitutional Nb-Doping
• Molecular beam epitaxy growth and scanning tunneling microscopy study of TiSe${}_2$ ultrathin films
• Ising superconductors: Interplay of magnetic field, triplet channels, and disorder
• Phase evolution and superconductivity enhancement in Se-substituted MoTe${}_2$ thin films
• Bound hole states associated to individual vanadium atoms incorporated into monolayer WSe${}_2$
• Tunneling of Bloch electrons through vacuum barrier
• Strong In-plane Anisotropy in the Electronic Properties of Doped Transition Metal Dichalcogenides exhibited in W1-xNbxS2

Cited by in corpus (3)

• Ising superconductivity: a first-principles perspective
• Engineering two-dimensional materials from single-layer NbS${}_2$
• Alloying 2D VSe2 with Pt: from a charge density wave state to a disordered insulator