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Modeling magnetism and electric field effects in 2D chromium iodide

JUL 03, 2020
Using first principles, researchers show the differing results in the various interlayer combinations of graphene and hexagonal nitride.
Modeling magnetism and electric field effects in 2D chromium iodide internal name

Modeling magnetism and electric field effects in 2D chromium iodide lead image

As conventional transistors reach their limit, 2D materials are becoming a prime focus in developing next-generation quantum devices, such as tunneling field-effect transistors. The magnetic properties in spintronic materials can be controlled by applying an electric field in a process known as gating.

Cheng et al. used first principles to model and simulate the electric gate effects on 2D chromium iodide (CrI3) sandwiched between graphene and hexagonal boron nitride (h-BN).

When the dimension of CrI3 reduces from 3D to 2D, the local Coulomb interaction increases by about 1 electron volt and goes from being ferromagnetic to antiferromagnetic (AFM). As a 2D material, CrI3 exhibits antiferromagnetic (AFM) interlayer coupling that can be tuned by the application of magnetic field, gate electric field or pressure.

The authors compared bare bilayer CrI3 using interlayer combinations of graphene, known for its extraordinary conducting properties, and h-BN, an insulator. They found that inserting bilayer CrI3 between two graphene sheets prohibits a magnetic phase transition in relatively low electric fields due to electrostatic shielding.

However, if bilayer CrI3 is placed between a graphene sheet as the top layer and an h-BN sheet as the bottom layer, it became possible to drive a magnetic phase transition using an electric field, although it still requires a larger field than that for bare bilayer CrI3. Before the magnetic phase transition, the magnetic moment in the AFM state increases at a smaller electric field due to charge transfer between graphene and bilayer CrI3.

The researchers plan to next investigate electron tunneling in the same materials.

Source: “First-principles study of magnetism and electric field effects in 2D systems,” by Hai-Ping Cheng, Shuanglong Liu, Xiao Chen, Long Zhang, and James N. Fry, AVS Quantum Science (2020). The article can be accessed at https://doi.org/10.1116/5.0009316 .

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