411 research outputs found
Manipulation of electronic and magnetic properties of MC (M=Hf, Nb, Sc, Ta, Ti, V, Zr) monolayer by applying mechanical strains
Tuning the electronic and magnetic properties of a material through strain
engineering is an effective strategy to enhance the performance of electronic
and spintronic devices. Recently synthesized two-dimensional transition metal
carbides MC (M=Hf, Nb, Sc, Ta, Ti, V, Zr), known as MXenes, has aroused
increasingly attentions in nanoelectronic technology due to their unusual
properties. In this paper, first-principles calculations based on density
functional theory are carried out to investigate the electronic and magnetic
properties of MC subjected to biaxial symmetric mechanical strains. At the
strain-free state, all these MXenes exhibit no spontaneous magnetism except for
TiC and ZrC which show a magnetic moment of 1.92 and 1.25 /unit,
respectively. As the tensile strain increases, the magnetic moments of MXenes
are greatly enhanced and a transition from nonmagnetism to ferromagnetism is
observed for those nonmagnetic MXenes at zero strains. The most distinct
transition is found in HfC, in which the magnetic moment is elevated to 1.5
/unit at a strain of 15%. We further show that the magnetic properties
of HfC are attributed to the band shift mainly composed of Hf(5) states.
This strain-tunable magnetism can be utilized to design future spintronics
based on MXenes
Gas adsorption on MoS2 monolayer from first-principles calculations
First-principles calculations within density functional theory (DFT) have
been carried out to investigate the adsorption of various gas molecules
including CO, CO2, NH3, NO and NO2 on MoS2 monolayer in order to fully exploit
the gas sensing capabilities of MoS2. By including van der Waals (vdW)
interactions between gas molecules and MoS2, we find that only NO and NO2 can
bind strongly to MoS2 sheet with large adsorption energies, which is in line
with experimental observations. The charge transfer and the variation of
electronic structures are discussed in view of the density of states and
molecular orbitals of the gas molecules. Our results thus provide a theoretical
basis for the potential applications of MoS2 monolayer in gas sensing and give
an explanation for recent experimental findings.Comment: 15 pages, 5 figure
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