Magnetic Phase Transition in Strained Two-Dimensional CrSeTe Monolayer

Tunable magnetic phase transition in two-dimensional materials is a fascinating subject of research.We perform first-principle calculations based on density functional theory to clarify the magnetic property of CrSeTe monolayer modulated by the biaxial compressive strain.Based on the stable structure confirmed by the phonon calculation,CrSeTe is determined to be a ferromagnetic metal that undergoes a phase transition from a ferromagnetic state to an antiferromagnetic state with nearly 2.75%compressive strain.We identify the stress-magnetism behavior originating from the changes in interactions between the nearest-neighboring Cr atoms(J_(1)) and the next-nearest-neighboring Cr atoms(J_(2)).Through Monte Carlo simulation,we find that the Curie temperature of the CrSeTe monolayer is 160 K.The CrSeTe monolayer could be an intriguing platform for the two-dimensional systems and potential spintronic material.

Enhancement of Curie Temperature under Built-in Electric Field in Multi-Functional Janus Vanadium Dichalcogenides

Functionalized two-dimensional materials with multiferroicity are highly desired to be next-generation electronic devices.Here we theoretically predict a family of Janus vanadium dichalcogenides VXX'(X/X'=S,Se,Te)monolayers with multiferroic properties,combing ferromagnetism,ferroelasticity and piezoelectricity.Due to the unpaired electrons on the V atom,the Janus VXX'monolayers have intrinsic long-range ferromagnetic orders.Particularly,the Curie temperature of 1T-VSeTe monolayer is up to 100 K,which is greatly higher than 2D 1T-VSe2 and 1T-VTe2.Furthermore,the six Janus VXX'monolayers have similar crater-like ferroelastic switching curves.Compared to black phosphorus,2H-VSSe monolayer has the similar ferroelastic switching signal and 4 times lower energy barrier.In addition,the out-of-plane piezoelectricity induced by the structure asymmetry in the vertical direction gives the 2H-VXX'monolayers the potential to be piezoelectric materials.It is found that a built-in electric field in the vertical direction due to the different electronegativity values of chalcogen atoms induces the changes of electronic structures,which leads to the appearance of three different types of band gaps in the three H-phase structures.Recently,the experimental growth of the Janus MoSSe monolayers and the electrochemical exfoliation of ferromagnetic monolayered VSe2 make the Janus VXX'monolayers possibly fabricated in experiments.