Substrate induced electronic phase transitions of CrI$$_{3}$$ based van der Waals heterostructures

Abstract

We perform first principle density functional theory calculations to predict the substrate induced electronic phase transitions of CrI$$_{3}$$ 3 based 2-D heterostructures. We adsorb graphene and MoS$$_{2}$$ 2 on novel 2-D ferromagnetic semiconductor—CrI$$_{3}$$ 3 and investigate the electronic and magnetic properties of these heterostructures with and without spin orbit coupling (SOC). We find that when strained MoS$$_{2}$$ 2 is adsorbed on CrI$$_{3}$$ 3 , the spin dependent band gap which is a characteristic of CrI$$_{3}$$ 3 , ceases to remain. The bandgap of the heterostructure reduces drastically ($$\sim$$ ∼ 70%) and the heterostructure shows an indirect, spin-independent bandgap of $$\sim$$ ∼ 0.5 eV. The heterostructure remains magnetic (with and without SOC) with the magnetic moment localized primarily on CrI$$_{3}$$ 3 . Adsorption of graphene on CrI$$_{3}$$ 3 induces an electronic phase transition of the subsequent heterostructure to a ferromagnetic metal in both the spin configurations with magnetic moment localized on CrI$$_{3}$$ 3 . The SOC induced interaction opens a bandgap of $$\sim$$ ∼ 30 meV in the Dirac cone of graphene, which allows us to visualize Chern insulating states without reducing van der Waals gap.

Effect of Magnetic Tuning and Induced Charge Transfer Isotropy in a CrI3-Based 2D Trilayer Heterostructure

“…This was done by matching the lattice parameters of the interfaces and distributing the strain equally among the interlayers (tensile and compressive). A 3 × 3 graphene adsorbed on a 1 × 1 CrI 3 allows four possible configurations and has a lattice constant of 7.194 Å . The most stable configuration is when the graphene ring (highlighted in orange in Figure (a)) is on top of a Cr atom of CrI 3 .…”

“…Therefore, we consider the most stable bilayer configurations to design a trilayer where CrI 3 is sandwiched between graphene (in the top configuration) and MoS 2 (in the hollow configuration), and the lateral periodicity is determined. This further gives rise to two possible supercell structures with respect to the trilayer which is shown in Figure S2 of the SI.…”

“…We perform first principle calculations based on ab initio density functional theory (DFT) implemented within the Quantum Espresso platform . A generalized gradient approximation (GGA) with Perdew–Burke–Ernzerhof (PBE) exchange correlation functional and a plane wave basis set is considered . We also perform electronic structure calculations using GGA+U and HSE06 methods (as shown in the Supporting Information (SI)) to take into account the extended d orbitals of Cr, and we find no significant deviations with respect to GGA method close to the Fermi level.…”

“…Chern insulator states can be induced for graphene/CrI 3 upon applying external pressure ranging between 1.4 and 18 GPa . Our previous study on graphene/CrI 3 suggests that spin–orbit interactions introduce a bandgap of ∼30 meV in the Dirac cone of graphene, − resulting in Chern insulator states in the heterostructure. Further, studies with CrI 3 /MoS 2 show a reduced spin-independent indirect bandgap of ∼0.5 eV due to planar lattice strain .…”

“…Our previous study on graphene/CrI 3 suggests that spin–orbit interactions introduce a bandgap of ∼30 meV in the Dirac cone of graphene, − resulting in Chern insulator states in the heterostructure. Further, studies with CrI 3 /MoS 2 show a reduced spin-independent indirect bandgap of ∼0.5 eV due to planar lattice strain . Furthermore, CrI 3 -based van der Waals heterostructures present several potential areas of research and applications.…”