Tuning MgB<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>(0001) surface states through surface termination

Despoja, Vito; Mowbray, D. J.; Silkin, Viatcheslav M.

doi:10.1103/physrevb.84.104514

Cited by 6 publications

(3 citation statements)

References 44 publications

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“…Here we have used the overlaps between the Kohn-Sham wave functions at successive k points n,k | n ,k+ k to differentiate between band crossings and avoided crossings, as described in Ref. 36.…”

Section: Methodsmentioning

confidence: 99%

TDDFT study of time-dependent and static screening in graphene

et al. 2012

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Time-dependent density functional theory (TDDFT) within the random phase approximation (RPA) is used to obtain the time evolution of the induced potential produce by the sudden formation of a C 1s core hole inside a graphene monolayer, and to show how the system reaches the equilibrium potential. The characteristic oscillations in the time-dependent screening potential are related to the excitations of π and σ + π plasmons as well as the low energy 2D plasmons in doped graphene. The equilibrium RPA screened potential is compared with the DFT effective potential, yielding good qualitative agreement. The self energy of a point charge near a graphene monolayer is shown to demonstrate an image potential type behavior, Ze/(z − z 0 ), down to very short distances (4 a.u.) above the graphene layer. Both results are found to agree near quantitatively with the DFT ground state energy shift of a Li + ion placed near a graphene monolayer.

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Section: Methodsmentioning

confidence: 99%

TDDFT study of time-dependent and static screening in graphene

et al. 2012

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“…A surface modification strategy may be necessary in order to improve surface stability of MgB 2 thin films. 58 Much effort has been focused on understanding the relation between the surface states and the superconductivity of thin film MgB 2 . 58-61 A hypothesis has been presented that ultrathin film MgB 2 can have different T c than bulk material, due to interaction between the surface electronic structure and the surface phonons of MgB 2 ultrathin film.…”

Section: Resultsmentioning

confidence: 99%

Electronic structure and surface properties ofMgB2(0001) upon oxygen adsorption

et al. 2018

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We use density-functional theory to investigate the bulk and surface properties of MgB2. The unique bonding structure of MgB2 is investigated by Bader's atoms-in-molecules, charge density difference, and occupancy projected band structure analyses. Oxygen adsorption on the chargedepleted surfaces of MgB2 is studied by a surface potential energy mapping method, reporting a complete map including low-symmetry binding sites. The B-terminated MgB2(0001) demonstrates reconstruction of the graphene-like B layer and the reconstructed geometry exposes a threefold site of the sub-surface Mg, making it accessible from the surface. Detailed reconstruction mechanisms are studied by simulated annealing method based on ab-initio molecular dynamics and nudged elastic band calculations. The surface clustering of B atoms significantly modifies the B 2p states to occupy low energy valence states. The present work emphasizes that a thorough understanding of the surface phase may explain an apparent inconsistency in the experimental surface characterization of MgB2. Furthermore, these results suggest that the surface passivation can be an important technical challenge when it comes to development of a superconducting device using MgB2.

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“…In the first case, we consider termination at the barium layer. To avoid doping the system, either half-filling of the surface sites or substitution with an alkali metal, as has been proposed in MgB 2 61 , is required. Calculations of both produce similar results; we present the latter, using potassium in place of barium, for ease of comparison.…”

Section: B Surfacementioning

confidence: 99%

BaSn2 : A wide-gap strong topological insulator

et al. 2017

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BaSn2 has been shown to form as layers of buckled stanene intercalated by barium ions 1 . However, despite an apparently straightforward synthesis and significant interest in stanene as a topological material, BaSn2 has been left largely unexplored, and has only recently been recognized as a potential topological insulator. Belonging to neither the lead nor bismuth chalcogenide families, it would represent a unique manifestation of the topological insulating phase. Here we present a detailed investigation of BaSn2, using both ab initio and experimental methods. First-principles calculations demonstrate that this overlooked material is a indeed strong topological insulator with a bulk band gap of 360meV, among the largest observed for topological insulators. We characterize the surface state dependence on termination chemistry, providing guidance for experimental efforts to measure and manipulate its topological properties. Additionally, through ab initio modeling and synthesis experiments we explore the stability and accessibility of this phase, revealing a complicated phase diagram that indicates a challenging path to obtaining single crystals.

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Tuning MgB2(0001) surface states through surface termination

Cited by 6 publications

References 44 publications

TDDFT study of time-dependent and static screening in graphene

TDDFT study of time-dependent and static screening in graphene

Electronic structure and surface properties ofMgB2(0001) upon oxygen adsorption

BaSn2 : A wide-gap strong topological insulator

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