Piezoelectricity and valley polarization in a semilithiated 2H-TiTe₂ monolayer with near room-temperature ferromagnetism

Abstract

Two-dimensional ferromagnetic semiconductors with coupled valley physics and piezoelectric responses offer unprecedented opportunities to miniaturize low-power multifunctional integrated devices. Prompted by epitaxial fabrication of nonmagnetic 2H-TiTe2 monolayer on the Au(111)...

Density Functional Theory Study of Topological Phase Transition and Valley Polarization in RuOHCl Monolayer: Implications for Valleytronics and Spintronics Devices

“…The above results indicate that the RuOHCl monolayer is an excellent FV material. Due to its in-plane magnetic anisotropy, the valley polarization in RuOHCl monolayer is nonspontaneous. , This means an external magnetic field is required to change the easy axis of magnetization from in-plane to out-of-plane, thereby realizing a valley polarization in the RuOHCl monolayer. When the magnetization of Ru atoms is along the − z direction, the energy band changes from spin-down to spin-up near the Fermi level, and valley polarization transfers to the K valley in the valence band with a value of −201 meV, as indicated in Figure c.…”

“…Notably, to realize the topological phase transition in RuOHCl monolayer under tensile strain, the easy axis of magnetization changes from in-plane to out-of-plane using an external magnetic field. 51,52 The above results indicate that it is important to choose a suitable substrate to effectively control the strain when preparing the RuOHCl monolayer. 2.6.…”

Ab Initio Discovery of Group IV–V Monolayers with Superlative Mechanical, Electronic, and Transport Properties

“…Thanks to the spin-valley locking, the SOC-induced valley spin splitting yields the optical transition energies of 577/808 meV for α′-SnAs, 683/998 meV for α′-SnSb, 683/1309 meV for α′-PbAs, and 683/1429 meV for α′-PbSb at the spin-down/spin-up channel level. The irradiation of circularly polarized infrared light on these four semiconductors can thus break the time-reversal symmetry to generate valley polarization, − indicative of their great potential as reliable alternatives to monolayers of 2H-TMDCs for valley-based electronic and optoelectronic applications.…”

Large valley polarization and the valley-dependent Hall effect in a Janus TiTeBr monolayer

“…Since 2017, Janus TMD materials such as Mo(S, Se) 2 and W(S, Se) 2 monolayers have been synthesized, 24,25 noting that the Janus features provide a greater degree of freedom to modulate the magnetic state. 26 Inspired by theoretical study on Cr-based dichalcogenide halides and Ti-based magnetic materials, 27–30 it is possible to change the valence state of transition metal ions to induce magnetic order in non-magnetic TMDs through haloid Janus substitution, a promising platform to design many more ferrovalley materials.…”