Quantifying the rigidity of 2D carbides (MXenes)

2020 ◽  
Vol 22 (4) ◽  
pp. 2115-2121 ◽  
Author(s):  
Tao Hu ◽  
Jinxing Yang ◽  
Wu Li ◽  
Xiaohui Wang ◽  
Chang Ming Li
Keyword(s):  
First Principles ◽  
First Principles Calculations ◽  
Out Of Plane

The intrinsic in-plane stiffness (C) and out-of-plane rigidity (D) of four typical MXenes are quantified by first-principles calculations, with both exhibiting a strong thickness-dependent character.

Magnetism of elemental two-dimensional metals

2021 ◽  
Vol 9 (13) ◽  
pp. 4554-4561
Author(s):  
Yinti Ren ◽  
Liang Hu ◽  
Yangfan Shao ◽  
Yijian Hu ◽  
Li Huang ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Coordination Number ◽  
First Principles ◽  
Energy Band ◽  
Two Dimensional ◽  
First Principles Calculations ◽  
Out Of Plane ◽  
D Orbitals

The magnetic properties of 45 2D metals are explored using first-principles calculations. Of the 45 2D metals, 18 are found to be magnetic due to a coordination number decrease and the energy band narrowing of the out-of-plane d orbitals.

scholarly journals Highly spin-polarized electronic structure and magnetic properties of Mn2.25Co0.75Al1−xGex Heusler alloys: first-principles calculations

RSC Advances ◽  
2020 ◽  
Vol 10 (38) ◽  
pp. 22556-22569
Author(s):  
Yue Wang ◽  
Liying Wang ◽  
Wenbo Mi
Keyword(s):  
First Principles ◽  
Heusler Alloys ◽  
Lattice Deformation ◽  
First Principles Calculations ◽  
Easy Magnetization ◽  
Magnetization Direction ◽  
Spin Polarized ◽  
Out Of Plane ◽  
Plane Direction ◽  
Easy Magnetization Direction

The complete spin polarizations of Mn2.25Co0.75Al1−xGex are proved to be robust against stoichiometric defect and lattice deformation, whose easy magnetization direction can be manipulated from in-plane direction to out-of-plane one under uniaxial strain.

scholarly journals Switchable Interlayer Magnetic Coupling of Bilayer CrI3

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2509
Author(s):  
Yue Jiang ◽  
Yandong Guo ◽  
Xiaohong Yan ◽  
Hongli Zeng ◽  
Liyan Lin ◽  
...  
Keyword(s):  
First Principles ◽  
Axial Strain ◽  
Magnetic Coupling ◽  
First Principles Calculations ◽  
Spintronic Devices ◽  
Stacking Order ◽  
Out Of Plane ◽  
Application Potential ◽  
Magnetic Couplings ◽  
Interlayer Magnetic Coupling

Due to the weak van der Waals (vdW) interlayer interaction, interfacial geometry of two-dimensional (2D) magnetic vdW materials can be freely assembled, and the stacking order between layers can be readily controlled, such as laterally shifting or rotating, which may trigger the variation of magnetic order. We investigate the H-type bilayer CrI3 where the two layers are aligned in anti-parallel directions. Based on first-principles calculations, we propose two states with different interlayer magnetic couplings, i.e., ferromagnetic and antiferromagnetic, and analyze the superexchange mechanism inside. It is found that the two magnetic coupling states are stacking-dependent, and could be switched by applying out-of-plane axial strain and electron doping. Our findings show great application potential in the design of heterostructural and spintronic devices based on 2D magnetic vdW materials.

Ab initio calculations of magnetic anisotropy of Co and Fe films on Cu and Pt surfaces

2020 ◽  
Vol 25 (4) ◽  
pp. 22-27
Author(s):  
Marina V. Mamonova ◽  
Irina A. Prudnikova
Keyword(s):  
Magnetic Anisotropy ◽  
First Principles ◽  
Software Package ◽  
Magnetic Characteristics ◽  
First Principles Calculations ◽  
Monolayer Films ◽  
Magnetic Anisotropy Energy ◽  
Plane Anisotropy ◽  
Out Of Plane ◽  
The Difference

In this work, the results of numerical first-principles calculations of the magnetic characteristics for Co and Fe monolayer films on Cu(100) and Pt(100) slabs by using the VASP software package are presented. The values of the difference in the total energy of antiferromagnetic and ferromagnetic configurations depending on the parameters of convergence and thickness of non-magnetic material are calculated. Favorable magnetic anisotropy energy and values of the magnetic moment of atoms in the Co/Cu/Co, Co/Pt/Co, and Pt/Co/Cu/Co/Pt structures are determined. The phenomenon of reorientation in the Co/Cu(100)/Co structure, when the in-plane anisotropy of the cobalt films changes to an out-of-plane anisotropy due to the incorporation of an ultrathin platinum film into the structure is confirmed.

scholarly journals Intertwined ferroelectricity and topological state in two-dimensional multilayer

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Yan Liang ◽  
Ning Mao ◽  
Ying Dai ◽  
Liangzhi Kou ◽  
Baibiao Huang ◽  
...  
Keyword(s):  
First Principles ◽  
Topological Insulators ◽  
Response Speed ◽  
First Principles Calculations ◽  
Design Guideline ◽  
Out Of Plane ◽  
Topological States ◽  
Topological State ◽  
Fundamental Research ◽  
Two Parameter

AbstractThe intertwined ferroelectricity and band topology will enable the non-volatile control of the topological states, which is of importance for nanoelectrics with low energy costing and high response speed. Nonetheless, the principle to design such system is unclear and the feasible approach to achieve the coexistence of two parameter orders is absent. Here, we propose a general paradigm to design 2D ferroelectric topological insulators by sliding topological multilayers on the basis of first-principles calculations. Taking trilayer Bi2Te3 as a model system, we show that in the van der Waals multilayer based 2D topological insulators, the in-plane and out-of-plane ferroelectricity can be induced through a specific interlayer sliding, to enable the coexistence of ferroelectric and topological orders. The strong coupling of the order parameters renders the topological states sensitive to polarization flip, realizing non-volatile ferroelectric control of topological properties. The revealed design-guideline and ferroelectric-topological coupling not only are useful for the fundamental research of the coupled ferroelectric and topological physics in 2D lattices, but also enable innovative applications in nanodevices.

scholarly journals First principles modeling of pure black phosphorus devices under pressure

2019 ◽  
Vol 10 ◽  
pp. 1943-1951 ◽  
Author(s):  
Ximing Rong ◽  
Zhizhou Yu ◽  
Zewen Wu ◽  
Junjun Li ◽  
Bin Wang ◽  
...  
Keyword(s):  
First Principles ◽  
Pressure Ratio ◽  
Electronic Devices ◽  
Pressure Sensors ◽  
Real Space ◽  
Black Phosphorus ◽  
First Principles Calculations ◽  
Out Of Plane ◽  
Band Alignments ◽  
Low Dimensional

Black phosphorus (BP) has a pressure-dependent bandgap width and shows the potential for applications as a low-dimensional pressure sensor. We built two kinds of pure BP devices with zigzag or armchair conformation, and explored their pressure-dependent conductance in detail by using first principles calculations. The zigzag BP devices and the armchair BP devices exhibit different conductance–pressure relationships. For the zigzag BP devices conductance is robust against stress when the out-of-plane pressure ratio is less than 15%, and then increases rapidly until the conductive channels are fully opened. For the armchair pure BP devices conductance decreases at first by six orders of magnitude under increasing pressure and then increases quickly with further increase of pressure until the devices enter the on-state. This shows that the pure zigzag BP devices are more suitable for the application as flexible electronic devices with almost constant conductance under small pressure, while armchair BP devices can serve as bidirectional pressure sensors. Real-space distributions of band alignments were explored to understand the different pressure-related properties. We fitted a set of parameters based on the results from the empirical Wentzel–Kramers–Brillouin method, which provides an effortless approximation to quantitatively predict the pressure-related behaviors of large pure BP devices.

Intrinsic Thermal Conductivity of Wurtzite AlxGa1-xN, InxGa1-xN and InxAl1-xN From First-Principles Calculation

2015 ◽  
Author(s):  
Jinlong Ma ◽  
Baoling Huang ◽  
Wu Li ◽  
Xiaobing Luo
Keyword(s):  
Thermal Conductivity ◽  
First Principles ◽  
Room Temperature ◽  
Mean Free Path ◽  
First Principles Calculation ◽  
First Principles Calculations ◽  
Out Of Plane ◽  
Pure Compounds ◽  
Crystal Model ◽  
Thermal Conductivities

The thermal conductivities of the alloys of wurtzite AlN, GaN and InN are usually analyzed with the virtual crystal model based on the values of the constituent compounds. However, latest experiments and calculations reveal that the thermal conductivity of wurtzite InN is about three times larger than the previously used value. Thus it is necessary to reanalyze the thermal conductivities of these alloys. In this work, the intrinsic thermal conductivities of AlxGa1−xN, InxGa1−xN and InxAl1−xN are calculated with first-principles calculations along with the virtual crystal treatment. It is found that the thermal conductivities of these alloys are strongly suppressed even after a small amount of alloying. For instance, the in-plane and out-of-plane thermal conductivities of In0.99Ga0.01 N are 66 Wm−1K−1 and 76 Wm−1K−1 respectively, while they are 40 Wm−1K−1 and 48 Wm−1 K−1 for In0.99Al0.01 N, compared with the corresponding values of 130 Wm−1 K−1 and 145 Wm−1 K−1 for bulk wurtzite InN. When the fraction x varies from 0.2 to 0.8, the thermal conductivities of the alloys do not change much. Additionally, the distribution of mean free path indicates that the size effect can persist up to 10μm for both pure compounds and their alloys at room temperature.

scholarly journals Magnetic order and critical temperature of substitutionally doped transition metal dichalcogenide monolayers

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Sabyasachi Tiwari ◽  
Maarten L. Van de Put ◽  
Bart Sorée ◽  
William G. Vandenberghe
Keyword(s):  
Transition Metal ◽  
First Principles ◽  
Room Temperature ◽  
Magnetic Order ◽  
Transition Metal Dichalcogenide ◽  
First Principles Calculations ◽  
Out Of Plane ◽  
Atomic Substitution ◽  
Mn Doped ◽  
Ordered State

AbstractUsing first-principles calculations, we investigate the magnetic order in two-dimensional (2D) transition-metal-dichalcogenide (TMD) monolayers: MoS2, MoSe2, MoTe2, WSe2, and WS2 substitutionally doped with period four transition-metals (Ti, V, Cr, Mn, Fe, Co, Ni). We uncover five distinct magnetically ordered states among the 35 distinct TMD-dopant pairs: the non-magnetic (NM), the ferromagnetic with out-of-plane spin polarization (Z FM), the out-of-plane polarized clustered FMs (clustered Z FM), the in-plane polarized FMs (X–Y FM), and the anti-ferromagnetic (AFM) state. Ni and Ti dopants result in an NM state for all considered TMDs, while Cr dopants result in an anti-ferromagnetically ordered state for all the TMDs. Most remarkably, we find that Fe, Mn, Co, and V result in an FM ordered state for all the TMDs, except for MoTe2. Finally, we show that V-doped MoSe2 and WSe2, and Mn-doped MoS2, are the most suitable candidates for realizing a room-temperature FM at a 16–18% atomic substitution.

Electronic Structure and X-ray Absorption Spectra of Rutile TiO2 Using First-Principles Calculations

2014 ◽  
Vol 52 (12) ◽  
pp. 1025-1029
Author(s):  
Min-Wook Oh ◽  
Tae-Gu Kang ◽  
Byungki Ryu ◽  
Ji Eun Lee ◽  
Sung-Jae Joo ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Absorption Spectra ◽  
First Principles ◽  
First Principles Calculations ◽  
Rutile Tio2 ◽  
X Ray ◽  
X Ray Absorption

To Bend or Not to Bend, the Dilemma of Multiple Bonds

2019 ◽  
Author(s):  
Michele Pizzocchero ◽  
Matteo Bonfanti ◽  
Rocco Martinazzo
Keyword(s):  
First Principles ◽  
2D Materials ◽  
Main Group ◽  
First Principles Calculations ◽  
Group 14 ◽  
Multiple Bonds ◽  
Main Group Elements ◽  
Structural Distortions

The manuscript addresses the issue of the structural distortions occurring at multiple bonds between high main group elements, focusing on group 14. These distortions are known as trans-bending in silenes, disilenes and higher group analogues, and buckling in 2D materials likes silicene and germanene. A simple but correlated \sigma + \pi model is developed and validated with first-principles calculations, and used to explain the different behaviour of second- and higher- row elements.

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