Dialkali-Metal Monochalcogenide Semiconductors with High Mobility and Tunable Magnetism

Abstract

The discovery of archetypal two-dimensional (2D) materials provides enormous opportunities in both fundamental breakthroughs and device applications, as evident by the research booming in graphene, atomically thin transition-metal chalcogenides, and few-layer black phosphorous in the past decade. Here, we report a new, large family of semiconducting dialkali-metal monochalcogenides (DMMCs) with an inherent A${}_2$X monolayer structure, in which two alkali sub-monolayers form hexagonal close packing and sandwich the triangular chalcogen atomic plane. Such unique lattice structure leads to extraordinary physical properties, such as good dynamical and thermal stability, visible to near-infrared light energy gap, high electron mobility (e.g. $1.87\times 10^4$ cm${}^2$V${}^{-1}$S${}^{-1}$ in K${}_2$O). Most strikingly, DMMC monolayers (MLs) host extended van Hove singularities near the valence band (VB) edge, which can be readily accessed by moderate hole doping of $\sim 1.0\times 10^{13}$ cm${}^{-2}$. Once the critical points are reached, DMMC MLs undergo spontaneous ferromagnetic transition when the top VBs become fully spin-polarized by strong exchange interactions. Such gate tunable magnetism in DMMC MLs are promising for exploring novel device concepts in spintronics, electronics and optoelectronics.

arXiv comment18 pages, 4 figures, and 1 table

References in corpus (21)

• Electric Field Effect in Atomically Thin Carbon Films
• Two-Dimensional Gas of Massless Dirac Fermions in Graphene
• Atomically thin MoS2: A new direct-gap semiconductor
• Experimental Observation of Quantum Hall Effect and Berry's Phase in Graphene
• Van der Waals heterostructures
• Black phosphorus field-effect transistors
• Layer-dependent Ferromagnetism in a van der Waals Crystal down to the Monolayer Limit
• Discovery of intrinsic ferromagnetism in 2D van der Waals crystals
• Van der Waals density functionals applied to solids
• High-mobility transport anisotropy and linear dichroism in few-layer black phosphorus
• Quantum Spin Hall Effect in Silicene
• Excitons in atomically thin transition metal dichalcogenides
• Epitaxial Growth of Two-Dimensional Stanene
• High Electron Mobility, Quantum Hall Effect and Anomalous Optical Response in Atomically Thin InSe
• The interlayer cohesive energy of graphite from thermal desorption of polyaromatic hydrocarbons
• Phosphorene analogues: isoelectronic two-dimensional group-IV monochalcogenides with orthorhombic structure
• Tunable Magnetism and Half-Metallicity in Hole-doped Monolayer GaSe
• Quantum Hall Effect in Black Phosphorus Two-dimensional Electron Gas
• Evolution of high-temperature superconductivity from low-Tc phase tuned by carrier concentration in FeSe thin flakes
• Defects controlled hole doping and multi-valley transport in SnSe single crystals
• Multiple Unpinned Dirac Points in Group-Va Single-layers with Phosphorene Structure

Cited by in corpus (2)

• KTlO: A metal shrouded 2D semiconductor with high carrier mobility and tunable magnetism
• Tunable Topological Energy Bands in 2D Dialkali-Metal Monoxides