Anisotropic optical property of ferroelectric BiOX(X = S,Se,Te) monolayer and strain engineering.

Based on the first-principles calculations, ferroelectricBi2O2X(X=S,Se,Te)monolayers with unequivalent in-plane lattice constants are confirmed to be the ground state, which is consistent with the experiment result (Ghosh20195703-09), and the anisotropic optical property is firstly investigated. We find that the polarizations ofBi2O2Xmonolayers points along the direction of-axis, andBi2O2Temonolayer process the largest polarization. Furthermore, both the biaxial and uniaxial strains are favor for the enhancement of polarization ofBi2O2Xmonolayers.

Coexisting Magnetism, Ferroelectric, and Ferrovalley Multiferroic in Stacking-Dependent Two-Dimensional Materials.

Two-dimensional (2D) multiferroic materials have widespread application prospects in facilitating the integration and miniaturization of nanodevices. However, the magnetic, ferroelectric, and ferrovalley properties in one 2D material are rarely coupled. Here, we propose a mechanism for manipulating magnetism, ferroelectric, and valley polarization by interlayer sliding in a 2D bilayer material.

Tailoring angle dependent ferroelectricity in nanoribbons of group-IV monochalcogenides.

Ferroelectricity is significant in low dimensional structures due to the potential applications in multifunctional nanodevices. In this work, the tailoring angle dependent ferroelectricity is systematically investigated for the nanoribbons and nanowires of puckered group-IV monochalcogenides MX (M =Ge,Sn; X =S,Se). Based on first-principles calculations, it is found that the ferroelectricity of nanoribbon and nanowire strongly depends on the tailoring angle.

Coexistence of polar distortion and conduction in doped 2D group-IV ferroelectrics: SiGe, SiSn, and GeSn.

Since the concept of ferroelectric metal predicted in the 1960s has been experimentally realized in the bulk Weyl semimetal WTe[Sharma2019, eaax5080], it is significant to find the ultrathin polar metal or ferroelectric metal due to the demand of miniature of electronic nanodevices. Here, 2D buckled monolayers composed of group-IV elements such as SiGe, SiSn, and GeSn are selected as prototype. Then, the stability of 2D ferroelectricity in the above monolayers are confirmed based on the results of first-principles calculations.

First-principles study of interface doping in ferroelectric junctions.

Effect of atomic monolayer insertion on the performance of ferroelectric tunneling junction is investigated in SrRuO3/BaTiO3/SrRuO3 heterostrucutures. Based on first-principles calculations, the atomic displacement, orbital occupancy, and ferroelectric polarization are studied. It is found that the ferroelectricity is enhanced when a (AlO2)(-) monolayer is inserted between the electrode SRO and the barrier BTO, where the relatively high mobility of doped holes effectively screen ferroelectric polarization.

Expansion dynamics in a one-dimensional hard-core boson model with three-body interactions.

Using the adaptive time-dependent density matrix renormalization group method, we numerically investigate the expansion dynamics of bosons in a one-dimensional hard-core boson model with three-body interactions. It is found that the bosons expand ballistically with weak interaction, which are obtained by local density and the radius Rn. It is shown that the expansion velocity V, obtained from Rn = Vt, is dependent on the number of bosons.