Two-dimensional CoSe structures: Intrinsic magnetism, strain-tunable anisotropic valleys, magnetic Weyl point, and antiferromagnetic metal state

Abstract

The interplay between magnetism, band topology, and electronic correlation in low dimensions has been a fascinating subject of research. Here, we propose two-dimensional (2D) material systems which demonstrate such an interesting interplay. Based on first-principles calculations and structural search algorithms, we identify three lowest energy 2D CoSe structures, termed as the $\alpha$-, $\beta$-, and $\gamma$-CoSe. {We show that $\alpha$- and $\beta$-CoSe are two rare examples of 2D antiferromagnetic metals, which are related to their Fermi surfaces nesting features, and meanwhile, $\gamma$-CoSe is a ferromagnetic metal. They possess a range of interesting physical properties, including anisotropic valleys connected by crystalline symmetries, strain-tunable valley polarization, strain-induced metal-semiconductor and/or magnetic phase transitions, as well as topological band features such as the magnetic Weyl point and the magnetic Weyl loop. Remarkably, all the topological features here are robust against spin-orbit coupling.} Some experimental aspects of our predictions have been discussed.

References in corpus (19)

• Layer-dependent Ferromagnetism in a van der Waals Crystal down to the Monolayer Limit
• Discovery of intrinsic ferromagnetism in 2D van der Waals crystals
• Gate-tunable Room-temperature Ferromagnetism in Two-dimensional Fe${}_3$GeTe${}_2$
• Bandgap Engineering of Strained Monolayer and Bilayer MoS2
• Electrical Control of 2D Magnetism in Bilayer CrI3
• Polaritons in layered 2D materials
• Interface induced high temperature superconductivity in single unit-cell FeSe films on SrTiO3
• Superconductivity in single-layer films of FeSe with a transition temperature above 100 K
• Atomistic spin model simulations of magnetic nanomaterials
• Phase Diagram and High Temperature Superconductivity at 65 K in Tuning Carrier Concentration of Single-Layer FeSe Films
• Interface-induced superconductivity and strain-dependent spin density wave in FeSe/SrTiO3 thin films
• Discovery of two-dimensional Dirac nodal line fermions in monolayer Cu2Si
• Critical role of substrate in the high temperature superconductivity of single layer FeSe on Nb:BaTiO${}_3$
• Type-II nodal loops: theory and material realization
• Two-dimensional Weyl Half Semimetal and Tunable Quantum Anomalous Hall Effect in Monolayer PtCl${}_3$
• Valley-Layer Coupling: A New Design Principle for Valleytronics
• Hourglass Weyl loops in two dimensions: Theory and material realization in monolayer GaTeI family
• Antiferromagnetic order in epitaxial FeSe films on SrTiO3
• Frustrated magnetism in tetragonal CoSe, analogue to superconducting FeSe

Cited by in corpus (3)

• Two-dimensional topological semimetals
• Tunable electronic and magnetic properties of thin Nb${}_3$I${}_8$ nanofilms: interplay between strain and thickness
• Transition from antiferromagnets to altermagnets: Symmetry-Breaking Theory