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 Ab Initio Study of the Electronic, Vibrational, and Mechanical Properties of the Magnesium Diboride Monolayer

2019 ◽  
Vol 4 (2) ◽  
pp. 37 ◽  
Author(s):  
Jelena Pešić ◽  
Igor Popov ◽  
Andrijana Šolajić ◽  
Vladimir Damljanović ◽  
Kurt Hingerl ◽  
...  
Keyword(s):  
Ab Initio ◽  
First Principles ◽  
Materials Science ◽  
Magnesium Diboride ◽  
Poisson Ratio ◽  
Single Layer ◽  
First Principles Calculations ◽  
Significant Interest ◽  
Science Community ◽  
Fundamental Research

Magnesium diboride gained significant interest in the materials science community after the discovery of its superconductivity, with an unusually high critical temperature of 39 K. Many aspects of the electronic properties and superconductivity of bulk MgB 2 and thin sheets of MgB 2 have been determined; however, a single layer of MgB 2 has not yet been fully theoretically investigated. Here, we present a detailed study of the structural, electronic, vibrational, and elastic properties of monolayer MgB 2 , based on ab initio methods. First-principles calculations reveal the importance of reduction of dimensionality on the properties of MgB 2 and thoroughly describe the properties of this novel 2D material. The presence of a negative Poisson ratio, higher density of states at the Fermi level, and a good dynamic stability under strain make the MgB 2 monolayer a prominent material, both for fundamental research and application studies.

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 Probing embedded topological modes in bulk-like GeTe-Sb2Te3 heterostructures

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Hisao Nakamura ◽  
Johannes Hofmann ◽  
Nobuki Inoue ◽  
Sebastian Koelling ◽  
Paul M. Koenraad ◽  
...  
Keyword(s):  
Topological Insulator ◽  
First Principles ◽  
Atom Probe ◽  
Photoemission Spectroscopy ◽  
Band Offset ◽  
First Principles Calculations ◽  
Vacuum Interface ◽  
Topological States ◽  
Experimental Findings ◽  
Thick Layers

AbstractThe interface between topological and normal insulators hosts metallic states that appear due to the change in band topology. While topological states at a surface, i.e., a topological insulator-air/vacuum interface, have been studied intensely, topological states at a solid-solid interface have been less explored. Here we combine experiment and theory to study such embedded topological states (ETSs) in heterostructures of GeTe (normal insulator) and $$\hbox {Sb}_2$$ Sb 2 $$\hbox {Te}_3$$ Te 3 (topological insulator). We analyse their dependence on the interface and their confinement characteristics. First, to characterise the heterostructures, we evaluate the GeTe-Sb$$_2$$ 2 Te$$_3$$ 3 band offset using X-ray photoemission spectroscopy, and chart the elemental composition using atom probe tomography. We then use first-principles to independently calculate the band offset and also parametrise the band structure within a four-band continuum model. Our analysis reveals, strikingly, that under realistic conditions, the interfacial topological modes are delocalised over many lattice spacings. In addition, the first-principles calculations indicate that the ETSs are relatively robust to disorder and this may have practical ramifications. Our study provides insights into how to manipulate topological modes in heterostructures and also provides a basis for recent experimental findings [Nguyen et al. Sci. Rep. 6, 27716 (2016)] where ETSs were seen to couple over thick layers.

Topological properties of Sb(111) surface: A first-principles study

2021 ◽  
Author(s):  
Wang Shuangxi ◽  
Zhang Ping
Keyword(s):  
Time Reversal ◽  
First Principles ◽  
Density Functional ◽  
Bilayer Film ◽  
Time Reversal Symmetry ◽  
First Principles Calculations ◽  
Topological Properties ◽  
Functional Theory ◽  
Topological States ◽  
Reduced Surface

Abstract First-principles calculations based on density functional theory were performed to systematically study the electronic properties of the thin film of antimony in (111) orientation. Considering the spinorbit interaction, for stoichiometric surface, the topological states keep robust for six-bilayer case, and can be recovered in the three-bilayer film, which are guaranteed by time-reversal symmetry and inverse symmetry. For reduced surface doped by non-magnetic Bi or magnetic Mn atom, localized three-fold symmetric features can be identified. Moreover, band structures show that the non-trivial topological states stand for non-magnetic substitutional Bi atom, while can be eliminated by adsorbed or substitutional magnetic Mn atom.

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.

Sign in / Sign up

Export Citation Format

Share Document