Design of Two-Dimensional Multiferroics with Direct Polarization-Magnetization Coupling

Two-dimensional ferroelectricity induced by octahedral rotation distortion in perovskite oxides

“…Therefore, not all soft modes can generate energy gain, which may be related to the fact that the anharmonic effect is not considered in the calculation of phonon band structures. Similar phenomena have also been found in other perovskite and layered perovskite oxides [30,31,40].…”

“…The reversal of polarization can be caused by switching the senses of rotation of IR or tilt mode individually. Both modes can be reversed by a one-step (OS) or multi-steps (MS) switching [30,31]. The reversal of IR mode via MS refers to the change of the octahedral rotation direction in the upper and lower layers sequentially, so it undergoes a nonpolar phase established by OR plus tilt modes.…”

“…This improper ferroelectricity has been demonstrated in layered perovskites and perovskite superlattice [23][24][25][26][27][28], but is absent in perovskite bulks due to the preservation of inversion symmetry by octahedral rotation. Until recently, theoretical studies suggested that octahedral-rotation induced ferroelectricity can occur in 2D perovskites [29][30][31]. However, there are still some remaining issues to be resolved, such as the key influencing factors and the universality of this ferroelectricity.…”

Computational design of two‐dimensional magnetic materials

“…Although the coupling of magnetic and electrical properties is generally observed in 2D materials, however, there are very few multiferroics. Theoretical calculations indicated that single‐layer CuMP 2 X 6 (M = Cr and V; X = S and Se), 113 ReWCl 6 , ReWBr 6 , 114 and bilayer MoN 2 , Cr 2 NO 2 115 and Ca 3 FeOsO 7 116 were ferromagnetic and ferroelectric. Subsequently, 2D CuCrP 2 S 6 nanosheets (Figure 6(a)) were prepared and identified to be a multiferroic semiconductor, 117 in consistent with previous theoretical prediction.…”

Spin-gapless semiconducting Cl-intercalated phosphorene bilayer: a perfect candidate material to identify its ferroelectric states by spin-Seebeck currents

“…[4][5][6][7] Fortunately, the development of two-dimensional (2D) materials provides us new material plateaus to manipulate magnetoelectric couplings, which can contribute to overcome the above conflict and provides us with new opportunities to design new-generation multifunctional materials. 8,9 On the other side, towards realistic device applications, apart from the FE and FM states mentioned above, 2D materials possessing semiconducting properties are also highly desirable, owing to their high carrier mobilities, tunable electronic structures, and suitable band gaps controlled easily by gate voltage. [10][11][12][13][14][15][16] A famous class of 2D material samples are transition-metal disulfides (TMDs), in which the energy gaps can be tuned by the number of layers, and the corresponding magnetic structures can be changed significantly as their thicknesses are reduced to monoatomic ones.…”