Controlling Topological States in Topological/Normal Insulator Heterostructures

Costa, Marcio; Costa, A. T.; Freitas, Walter A.; Schmidt, T. M.; Nardelli, Marco Buongiorno; Fazzio, A.

doi:10.1021/acsomega.8b01836

Cited by 14 publications

(11 citation statements)

References 44 publications

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“…Gap size, SOC strength, work function difference, and relative thickness 20 of the CI and TI layers contribute to determine the properties of the resulting interface, as they drive the hybridization among atomic orbitals at the two sides of the interface. Structural aspects are also important: huge changes in the electronic structure have been predicted 21,22 and experimentally reported as being due to lattice strain and to the relative orientation of the two lattices 23 .…”

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confidence: 99%

Topologization of β-antimonene on Bi2Se3 via proximity effects

Holtgrewe

Mahatha

Sheverdyaeva

et al. 2020

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Topological surface states usually emerge at the boundary between a topological and a conventional insulator. Their precise physical character and spatial localization depend on the complex interplay between the chemical, structural and electronic properties of the two insulators in contact. Using a lattice-matched heterointerface of single and double bilayers of β-antimonene and bismuth selenide, we perform a comprehensive experimental and theoretical study of the chiral surface states by means of microscopy and spectroscopic measurements complemented by first-principles calculations. We demonstrate that, although β-antimonene is a trivial insulator in its free-standing form, it inherits the unique symmetry-protected spin texture from the substrate via a proximity effect that induces outward migration of the topological state. This "topologization" of β-antimonene is found to be driven by the hybridization of the bands from either side of the interface.

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confidence: 99%

Topologization of β-antimonene on Bi2Se3 via proximity effects

Holtgrewe

Mahatha

Sheverdyaeva

et al. 2020

Sci Rep

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“…This methodology has been successfully used in studies of other topological systems. 36,37 To characterize the system topological properties, we calculate the Z 2 invariant using the Wannier charge centers (WCCs) evolution method 38,39 implemented in the Z2Pack code. 40 We use PAO Hamiltonians as input to the Z2Pack code.…”

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confidence: 99%

Toward Realistic Amorphous Topological Insulators

et al. 2019

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The topological properties of materials are, until now, associated with the features of their crystalline structure, although translational symmetry is not an explicit requirement of the topological phases. Recent studies of hopping models on random lattices have demonstrated that amorphous model systems show a non-trivial topology. Using ab initio calculations we show that two-dimensional amorphous materials can also display topological insulator properties. More specifically, we present a realistic state-of-the-art study of the electronic and transport properties of amorphous bismuthene systems, showing that these materials are topological insulators. These systems are characterized by the topological index Z 2 = 1 and bulk-edge duality, and their linear conductance is quantized, G = 2e 2 /h, for Fermi energies within the topological gap. Our study opens the path to the experimental and theoretical investigation of amorphous topological insulator materials.

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“…Electronic bands calculated using these values reproduce with high-accuracy spin-orbit-coupling-induced gaps at highsymmetry points in the Brillouin zone calculated using DFT. The mean-field self-consistent ground state is obtained [34,44] by treating every component of the spin moment in each Fe atom as an independent variable. The resulting band structure, shown in Fig.…”

Section: Methodsmentioning

confidence: 99%

Nonreciprocal magnons in a two-dimensional crystal with out-of-plane magnetization

et al. 2020

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Nonreciprocal spin waves have a chiral asymmetry so that their energy is different for two opposite wave vectors. They are found in atomically thin ferromagnetic overlayers with in-plane magnetization and are linked to the antisymmetric Dzyaloshinskii-Moriya surface exchange. We use an itinerant fermion theory based on first-principles calculations to predict that nonreciprocal magnons can occur in Fe 3 GeTe 2 , the first stand-alone metallic two-dimensional crystal with out-of-plane magnetization. We find that both the energy and lifetime of magnons are nonreciprocal, and we predict that acoustic magnons can have lifetimes up to hundreds of picoseconds, orders of magnitude larger than in other conducting magnets.

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Controlling Topological States in Topological/Normal Insulator Heterostructures

Cited by 14 publications

References 44 publications

Topologization of β-antimonene on Bi2Se3 via proximity effects

Topologization of β-antimonene on Bi2Se3 via proximity effects

Toward Realistic Amorphous Topological Insulators

Nonreciprocal magnons in a two-dimensional crystal with out-of-plane magnetization

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