Strain Effects on the Two-Dimensional Cr₂N MXene: An Ab Initio Study

Abstract

Structural, electronic, and magnetic properties of two-dimensional Cr 2 N MXene under strain were studied. The uniaxial and biaxial strain was considered from −5 to 5%. Phonon dispersion was calculated; imaginary frequency was not found for both kinds of strain. Phonon density of states displays an interesting relation between strain and optical phonon gaps (OPGs), that it implies tunable thermal conductivity. When we apply biaxial tensile strain, the OPG increases; however, this is not appreciable under uniaxial strain. The electronic properties of the dynamically stable systems were investigated by calculating the band structure and electron localization function (ELF) along the (110) plane. The band structure showed a metallic behavior under compressive strain; nevertheless, under tensile strain, the system has a little indirect band gap of 0.16 eV. By analyzing, the ELF interactions between Cr–N are determined to be a weaker covalent bonding Cr 2 N under tensile strain. On the other hand, if the Cr atoms reduce or increase their self-distance, the magnetization alignment changes, also the magnetic anisotropy energy displays out-of-plane spin alignment. These properties extend the potential applications of Cr 2 N in the spintronic area as long as they can be grown on substrates with high lattice mismatch, conserving their magnetic properties.

Potential of MXenes as a novel material for spintronic devices: a review

“…These results also show the potential applications of Cr 2 N in spintronic applications as long as they can be grown on substrates with high lattice mismatch to wake up their magnetic properties. 110 In the monolayer M 2 X MXene group (M = Hf, Ti, Nb, Sc, Ta, V, Zr. X = C, N), the magnetic moment is strongly fluctuated by the applied strain, yet the metallic characteristics remain stable under high strain loading.…”

“…These results also show the potential applications of Cr 2 N in spintronic applications as long as they can be grown on substrates with high lattice mismatch to wake up their magnetic properties. 110…”

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

“…22,23 The strain effect is also considered to be an effective method to manipulate the electronic property and magnetocrystalline anisotropy (MCA) of 2D ferromagnetic materials. [24][25][26] For example, Sun et al…”

“…22,23 The strain effect is also considered to be an effective method to manipulate the electronic property and magnetocrystalline anisotropy (MCA) of 2D ferromagnetic materials. 24–26 For example, Sun et al theoretically reported that the MCA of single-layer (SL) Fe 2 I 2 can be effectively enhanced by applying tensile strain. 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).…”

Effective Method for the Determination of the Unit Cell Parameters of New MXenes

“…To date, more than 150 MAX phases formed from a combination of 14 M and 16 A elements have been reported [11]. Since 2017, researchers have synthesized about 30 new ordered MAX metal phases with double-transition-metal junctions and have studied their properties, including their magnetic [12][13][14], mechanical [15,16], electronic [17], and thermal characteristics [18]. The formation of solid solutions on M and/or X sites opens the possibility of synthesizing an infinite number of nonstoichiometric MXenes and the attractive possibility of fine-tuning the properties by mixing different transition metals or by creating carbonitrides [19].…”