Strain Tunable Electronic Band Structure and Magnetic Anisotropy of CrI₃ Bilayer

Abstract

Bilayer (BL) CrI3 attracts major attention among two dimensional (2D) materials due to the exhibition of unique interlayer antiferromagnetic ordering in contrast to other atomically thin films exhibiting long-range ferromagnetic ordering. It is believed that the high temperature monoclinic AB′ stacking plays the key role to induce unusual antiferromagnetic interlayer coupling in BL CrI3. The magnetic states of this system can be effectively controlled by external perturbations like magnetic field, electric field, carrier doping, strain etc. So, it is expected that strain effects can show a distinct behavior in the magnetic transition in BL CrI3. Here, we have studied the electronic and magnetic properties of BL CrI3 under in-plane biaxial and out-of-plane vertical strain from compression to stretch through density functional theory calculations. A compressive biaxial strain around −2.5 % can induce a transition from AFM to FM magnetic ground state which continues upto −6 % strain. Beyond this point, a second transition from FM to AFM1 state occurs. Detailed analysis of electronic structure indicates a strain induced direct to indirect band gap transition. Magnetic anisotropy energy (MAE) calculations show an out-of-plane easy axis for pristine CrI3 BL and this feature remains unchanged in the entire range of applied strain. It is also found that most of the perpendicular magnetic anisotropy contribution comes from the iodine atoms. Large MAE found in BL CrI3 may find useful applications in high density data storage devices.

Strain Engineering of Intrinsic Ferromagnetism in 2D van der Waals Materials

“…In addition, Webster et al [ 59 ] found that applying a tensile strain of 2.1% could increase the T C to 44 K, which was about 5 K higher than when no strain was applied. However, at a compressive strain of −4.1%, a FM to AFM phase transition, similar to CrCl 3 [ 59 , 63 , 64 ] and CrI 3 [ 59 , 70 , 71 , 72 ], also occurred.…”

“…The phase transition from FM to AFM under compressive strain (−3% or −5%) had also been discovered in the CrI 3 bilayer [ 70 ], similar to other previously reported systems [ 59 , 71 ]. In addition, Safi et al [ 72 ] found that the phase transition occurred at −6% compressive strain. More importantly, they also discovered a second phase transition point from FM to AFM, which occurred near −2.5% compressive strain.…”

“…More importantly, strengthening the guideline of strain-mediated FM in 2D van der Waals materials will promote the development of spintronics [ 6 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 ] and straintronics [ 12 , 19 ]. As shown in Figure 1 , we summarize three different kinds of 2D materials with intrinsic long-range FM order, including transition metal trihalides (CrCl 3 , CrBr 3 and CrI 3 ) [ 5 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 ], transition metals chalcogenides (Cr 2 Ge 2 Te 6 , Fe n GeTe 2 and CrTe 2 ) [ 42 , 43 , 44 , 45 , 46 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 <...…”

Theoretical prediction of two-dimensional ferromagnetic Mn2X2 (X = As, Sb) with strain-controlled magnetocrystalline anisotropy

“…27 Likewise, it has also been demonstrated that strain can be used to manipulate the MCA in CrCl 3 , CrBr 3 , CrI 3 , and CrSI monolayer (ML). [28][29][30] Notably, the experiment result discovered that the strain effect can switch the easy axis of CoCr 2 O 4 epitaxial thin films and a nonequilibrium strain distribution can drive the enhancement of MCA in ultrathin manganite (La, Sr) MnO 3 films. 31,32 In this work, we propose a family of 2D materials, i.e.…”

Influence of Mo Doping on Electronic and Magnetic Properties of Monolayer CrX3: A First-Principles Study

“…4,5 This limits their use in commercial applications. Hence, numerous efforts have been made to improve their magnetic properties, including doping, [6][7][8] defect, [9][10][11] strain engineering, [12][13][14][15][16] adsorption 17 etc. In fact, substitutional doping by 3d transtion metal (TM) or nonmagnetic atoms is found to be an effective tool to alter or modify the electronic and magnetic properties and thereby, inducing intrinsic magnetism in these materials.…”