Structural, electronic and magnetic properties of CrI3 nanotubes are studied using density functional theory.
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Tubes with large diameter have the strain energies below 0.05 eV/f.u. proposing their synthesis energetically possible.
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The nanotubes of both zigzag and armchair chirality exhibit ferromagnetic semiconducting properties.
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The electronic properties of CrI3 nanotubes can be tuned by size and applied external strain.
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Stretching of tubes leads to the enhancement of the FM-AFM exchange energy.
Abstract
In this paper, structural and electronic properties of CrI3 magnetic nanotubes (NTs) are studied using density functional theory. Both armchair and zigzag CrI3 nanotubes demonstrate a high correlation in strain energy between each other independently on accounting the Hubbard correction. The strain energies decrease with expansion of the tube diameter making the tubes’ synthesis with a diameter larger than 45 Å to be energetically possible. The nanotubes of both zigzag and armchair chirality are ferromagnetic semiconductors with band gaps close to that of the CrI3 monolayer. The band gaps are suppressed by reducing the tube diameters due to the structural stress leading to deformation of the Cr–I crystal field and changes in the bond lengths. The external strain can be utilized to flexibly tune the electronic properties of CrI3 nanotubes with the desired spin-up/spin-down band gap ratio. Strong distortion of the octahedral Cr–I crystal field under compression results in nontrivial behavior in the spin-up band gap of (4, 4) tube. Stretching of tubes leads to the enhancement of the exchange energy that should result in higher Curie temperature, therefore providing a good platform for potential applications in spintronic nanodevices.
