Intrinsic triferroicity in a two-dimensional lattice

Abstract

Intrinsic triferroicity is essential and highly sought for novel device applications, such as high-density multistate data storage. So far, the intrinsic triferroicity has only been discussed in three-dimensional systems. Herein on basis of first-principles, we report the intrinsic triferroicity in two-dimensional lattice. Being exfoliatable from the layered bulk, single-layer FeO2H is shown to be an intrinsically triferroic semiconductor, presenting antiferromagnetism, ferroelasticity and ferroelectricity simultaneously. Moreover, the directional control of its ferroelectric polarization is achievable by 90° reversible ferroelastic switching. In addition, single-layer FeO2H is identified to harbor in-plane piezoelectric effect. The unveiled phenomena and mechanism of triferroics in this two-dimensional system not only broaden the scientific and technological impact of triferroics but also enable a wide range of nanodevice applications.

Novel two-dimensional ferromagnetic materials CrX2 (X = O, S, Se) with high Curie temperature

“…Another important parameter, which reflects the ferroelastic performance and controls the signal intensity, is the reversible strain defined as | b / a − 1| × 100%. The reversible ferroelastic strain is calculated to be 38.7% and 42.2% for CrS 2 and CrSe 2 monolayers, respectively, which are comparable to that of BP 5 (41.4%), 72 phosphorene (37.9%), 73 CrSCl (36.5%), and CrSBr (31.5%) monolayers, 52 but larger than those of most 2D ferroelastic materials, such as FeO 2 H(23.5%), 77 Nb 2 GeTe 4 (22.1%), and Nb 2 SiTe 4 (24.4%), 78 and VNI (17.6%). 79 Hence, CrS 2 and CrSe 2 monolayers have ultrahigh reversible strain.…”

Theoretical Prediction of Antiferromagnetic Skyrmion Crystal in Janus Monolayer CrSi2N2As2

“…The isotropic exchange interaction parameter J is calculated to be −9.013 meV, which indicates an AFM neighboring interaction for monolayer CrSi 2 N 2 As 2 . It should be noted that the magnitude of J is comparable to those of NiI 2 , CrX (X = P, As, and Sb), and FeOOH . As schematically shown in Figure b, such an AFM neighboring interaction in a triangular lattice cannot result in an antiparallel arrangement for the magnetic moments of every two atoms at vertices of a unit equilateral triangle.…”

“…It should be noted that the magnitude of J is comparable to those of NiI 2 , 64 CrX (X = P, As, and Sb), 65 and FeOOH. 66 As schematically shown in Figure 1b, such an AFM neighboring interaction in a triangular lattice cannot result in an antiparallel arrangement for the magnetic moments of every two atoms at vertices of a unit equilateral triangle. This would lead to geometric frustration in monolayer CrSi 2 N 2 As 2 .…”

Intrinsic Multiferroic in VNI Monolayer

“…Generally, a high energy barrier has difficulty in manipulating the FA switch, while a too low energy barrier leads to phase instability in the FA state. The calculated FA switching barrier of the VNI monolayer is about 100.66 meV/atom, which is much higher than those of VAs (2.62 meV per V atom), 50 TcOBr (77 meV/atom), 51 and FeO 2 H (54 meV/atom) 52 monolayers but lower than that of phosphorene (200 meV/atom) 9 and α-HfPI (141 meV/ atom) 53 monolayers. Therefore, the present moderate energy barrier endows the 2D VNI monolayer with good ferroelasticity.…”