Topological insulator Bi<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>2</mml:mn></mml:msub></mml:math>Se<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>3</mml:mn></mml:msub></mml:math>(111) surface doped with transition metals: An<i>ab initio</i>investigation

Abdalla, Leonardo; Seixas, Leandro; Schmidt, T. M.; Miwa, R. H.; Fazzio, A.

doi:10.1103/physrevb.88.045312

Cited by 61 publications

(77 citation statements)

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“…Our calculations of the MAE reveal the out-of-plane magnetization direction for both cases (see Fig. 3), which is in good agreement with results of recent first-principles calculations [10]. This opens the band gap, which was estimated in our calculations at 5% chromium concentration to be 4.5 meV and 1.2 meV for the substitutional and interstitial Cr impurities, respectively.…”

Section: Magnetic Impurity At the Bi 2 Se 3 (0001) Surfacesupporting

confidence: 91%

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Magnetic fluctuations in topological insulators with ordered magnetic adatoms: Cr on Bi2Se3from first principles

et al. 2014

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We consider a system consisting of a topological insulator with an array of magnetic adatoms interacting with the surface states of electrons. We find that the indirect coupling of the magnetic impurities results in a ferromagnetic ordering of the magnetic moments and is also responsible for the unusual linear dispersion of the surface magnons. We also show that the interaction of magnons with surface electrons essentially renormalizes the electron energy spectrum. The renormalized spectrum is nonlinear and can be characterized by a negative effective mass of electrons and holes for any k = 0. The electron velocity near the Dirac point depends on the electron-magnon coupling.

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Section: Magnetic Impurity At the Bi 2 Se 3 (0001) Surfacesupporting

confidence: 91%

“…A further interesting situation is that of periodically ordered magnetic impurities at the surface of a TI [10]. In this case the translation symmetry is still preserved.…”

Section: Introductionmentioning

confidence: 99%

Magnetic fluctuations in topological insulators with ordered magnetic adatoms: Cr on Bi2Se3from first principles

et al. 2014

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“…4(a), for the electronic states parallel to the Γ-M direction, we find (i) positive (negative) values of S n,x (k) for the occupied (empty) states, while (ii) S n,y (k) = S n,z (k) = 0; whereas for k parallel to the Γ-K direction, we find (iii) negative (positive) values of S n,y (k) for the occupied (empty) states, (iv) S n,x (k) = 0, and (v) S n,z (k) values are negligible around the Γ-point. Such a picture of S n,α (k) , for the TSSs lying at the (py-Bi 2 Se 3 ) 1 /(Bi 2 Se 3 ) 5 interface, is practically the same as that obtained for the TSSs on the Bi 2 Se 3 (111) surface 21,23 . We now propose a mechanism to gain control over the topologically protected metallic states in (pyBi 2 Se 3 ) m /(Bi 2 Se 3 ) n .…”

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confidence: 75%

Pyridine intercalated Bi₂Se₃heterostructures: controlling the topologically protected states

Oliveira¹,

Miwa²

2015

Nanotechnology

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We use ab initio simulations to investigate the incorporation of pyridine molecules (C 5 H 5 N) in the van der Waals gaps of Bi 2 Se 3 . The intercalated pyridine molecules increase the separation distance between the Bi 2 Se 3 quintuple layers (QLs), suppressing the parity inversion of the electronic states at the Γ-point. We find that the intercalated region becomes a trivial insulator. By combining the pristine Bi 2 Se 3 region with the one intercalated by the molecules, we have a non-trivial/trivial heterojunction characterized by the presence of (topologically protected) metallic states at the interfacial region. Next we apply an external compressive pressure to the system, and the results are (i) a decrease on the separation distance between the QLs intercalated by pyridine molecules, and (ii) the metallic states are shifted toward the bulk region, turning the system back to insulator. That is, through a suitable tuning of the external pressure in Bi 2 Se 3 , intercalated by pyridine molecules, we can control its topological properties; turning-on and -off the topologically protected metallic states lying at the non-trivial/trivial interface.Three dimensional topological insulators (TIs) are insulator materials in the bulk phase, but they present metallic topological surface states (TSSs), which are protected by time-reversal symmetry; as a result backscattering processes by time-reversal invariant impurities or defects are forbidden 1 . These materials are of great promise for spintronics applications, due to the formation of nearly dissipationless spin-polarized surface current 2 . Currently, Bi 2 Se 3 is one of the most investigated TI due to its large band gap (∼ 0.3 eV), nearly idealized single Dirac cone and for being a pure compound 3-5 . Bi 2 Se 3 presents a rhombohedral structure composed by quintuple layers (QLs) of Se and Bi atoms, forming a sequence of Se-Bi-Se-Bi-Se atoms covalently bonded; these QLs are stacked along the c-axis of a hexagonal structure by van der Waals (vdW) interactions.Recent experiments have been exploring the possibility of inserting guest species in the vdW gaps of Bi 2 Se 3 , this process is known as intercalation. Koski et al. 6,7 have added various zerovalent metals in the vdW gaps of Bi 2 Se 3 nanoribbons, it is expected that new properties and/or tuning of the Bi 2 Se 3 properties can be achieved by intercalation, e.g. superconductivity 8 . Beside metals, molecules have been intercalated in Bi 2 Se 3 , for instance, it has been shown that pyridine molecules in Bi 2 Se 3 present interesting properties for optoelectronic applications 9 . In this work we aim to investigate the geometry and electronic structure of Bi 2 Se 3 intercalated by pyridine molecules (py-Bi 2 Se 3 ). Upon the presence of the pyridine molecules between the QLs, we find that the pyBi 2 Se 3 system becomes a trivial insulator. By considering a heterojunction composed by py-Bi 2 Se 3 and pristine Bi 2 Se 3 (py-Bi 2 Se 3 /Bi 2 Se 3 ), we analyze (i) the occurrence a) Electronic mail: igor.oliveira@...

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“…Although Cr is one of the most used dopant in the investigation between the surface states of TIs in general, and Bi2Se3 in particular [16,17,25,27,[30][31][32][33][34][35] which suggests that Bi-site substitution is energetically favorable for Cr [36]. However, the ARPES results do not show the broadening of the surface states or opening of a surface state energy gap as is the case for Cr bulk doping.…”

mentioning

confidence: 99%

Distinct effects of Cr bulk doping and surface deposition on the chemical environment and electronic structure of the topological insulator Bi2Se3

Yilmaz

Hines

Sun

et al. 2017

Applied Surface Science

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In this report, it is shown that Cr doped into the bulk and Cr deposited on the surface of Bi2Se3 films produced by molecular beam epitaxy (MBE) have strikingly different effects on both the electronic structure and chemical environment. peaks indicative of two Cr sites. These striking differences suggests an interesting possibility that better control of doping at only near surface region may offer a path to quantum anomalous Hall states at higher temperatures than reported in the literature.

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Topological insulator Bi2Se3(111) surface doped with transition metals: Anab initioinvestigation

Cited by 61 publications

References 50 publications

Magnetic fluctuations in topological insulators with ordered magnetic adatoms: Cr on Bi2Se3from first principles

Magnetic fluctuations in topological insulators with ordered magnetic adatoms: Cr on Bi2Se3from first principles

Pyridine intercalated Bi₂Se₃heterostructures: controlling the topologically protected states

Distinct effects of Cr bulk doping and surface deposition on the chemical environment and electronic structure of the topological insulator Bi2Se3

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Topological insulator Bi2Se3(111) surface doped with transition metals: Anab initioinvestigation

Cited by 61 publications

References 50 publications

Magnetic fluctuations in topological insulators with ordered magnetic adatoms: Cr on Bi2Se3from first principles

Magnetic fluctuations in topological insulators with ordered magnetic adatoms: Cr on Bi2Se3from first principles

Pyridine intercalated Bi2Se3heterostructures: controlling the topologically protected states

Distinct effects of Cr bulk doping and surface deposition on the chemical environment and electronic structure of the topological insulator Bi2Se3

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Pyridine intercalated Bi₂Se₃heterostructures: controlling the topologically protected states