Best practices for first-principles simulations of epitaxial inorganic interfaces

Dardzinski, Derek; Yu, Maituo; Moayedpour, Saeed; Marom, Noa

doi:10.1088/1361-648x/ac577b

Cited by 10 publications

(15 citation statements)

References 309 publications

(451 reference statements)

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“…We further note a strong dependence of the U values on the BO hyperparameters, as discussed in Ref. [98]. U ef f values used and Bayesian optimization convergence plots are shown in Table S1 and Figure S1, respectively.…”

Section: Methodssupporting

confidence: 56%

“…47 atomic layers of the semiconductor were used, based on previous band gap convergence studies [29,110,111]. The Heusler thickness was converged with respect to the density of states and magnetic moment, which should approach the bulk limit at the center of the slab [98]. For Ti 2 MnIn, the convergence test was performed with the TiIn termination.…”

Section: Resultsmentioning

confidence: 99%

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First Principles Study of the Electronic Structure of the Ni$_2$MnIn/InAs and Ti$_2$MnIn/InSb interfaces

Heischmidt¹,

Yu²,

Dardzinski³

et al. 2022

Preprint

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We present a first-principles study of the electronic and magnetic properties of epitaxial interfaces between the Heusler compounds Ti2MnIn and Ni2MnIn and the III-V semiconductors, InSb and InAs, respectively. We use density functional theory (DFT) with a machine-learned Hubbard U correction determined by Bayesian optimization. We evaluate these interfaces for prospective applications in Majorana-based quantum computing and spintronics. In both interfaces, states from the Heusler penetrate into the gap of the semiconductor, decaying within a few atomic layers. The magnetic interactions at the interface are weak and local in space and energy. Magnetic moments of less than 0.1 µB are induced in the two atomic layers closest to the interface. The induced spin polarization around the Fermi level of the semiconductor also decays within a few atomic layers. The decisive factor for the induced spin polarization around the Fermi level of the semiconductor is the spin polarization around the Fermi level in the Heusler, rather than the overall magnetic moment. As a result, the ferrimagnetic narrow-gap semiconductor Ti2MnIn induces a more significant spin polarization in the InSb than the ferromagnetic metal Ni2MnIn induces in the InAs. This is explained by the position of the transition metal d states in the Heusler with respect to the Fermi level. Based on our results, these interfaces are unlikely to be useful for Majorana devices but could be of interest for spintronics.

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Section: Methodssupporting

confidence: 56%

Section: Resultsmentioning

confidence: 99%

First Principles Study of the Electronic Structure of the Ni$_2$MnIn/InAs and Ti$_2$MnIn/InSb interfaces

Heischmidt¹,

Yu²,

Dardzinski³

et al. 2022

Preprint

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“…STM simulations were performed using the Tersoff and Hamann approximation, which states that the tunneling current is proportional to the local density of states (LDOS). 31 To generate the pristine 2×2 surface reconstruction, an In-terminated InAs(111) surface was constructed with 40 Å of vacuum, using an InAs lattice parameter of 6.0584 Å. Pseudohydrogen atoms with charges of 0.75 ewere appended to the bottom surface to passivate the dangling bonds that result from cleaving of the surface, 32 and a single In atom was then removed from the top surface. Next, ionic relaxation of the top four atomic layers and the pseudo-hydrogen positions was performed until the Hellman-Feynman forces acting on ions were below 0.001 eV/ Å.…”

Section: Methodsmentioning

confidence: 99%

Scale-dependent optimized homoepitaxy of InAs(111)A

Zelzer¹,

Batabyal²,

Dardzinski³

et al. 2022

Preprint

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We combined in-situ scanning tunneling microscopy (STM) with the conventional growth characterization methods of atomic force microscopy (AFM) and reflection high energy electron diffraction (RHEED) to simultaneously assess atomic scale impurities and the larger scale surface morphology of molecular beam epitaxy (MBE) grown homoepitaxial InAs(111)A. By keeping a constant substrate temperature and indium flux while increasing the As 2 flux, we find two differing MBE growth parameter regions for optimized surface roughness on the macro-and atomic scale. In particular, we show that a pure step-flow regime with strong suppression of hillock formation can be achieved, even on substrates without intentional offcut. On the other hand, an indium

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“…It has been shown that (semi-)local functionals fail to describe the bulk band structure of α-Sn correctly, specifically the band ordering and the orbital composition of the valence bands at the Γ point. DFT+U, hybrid functionals, or many-body perturbation theory within the GW approximation are necessary to obtain a correct description of the band structure [29,35,[57][58][59]. DFT+U simulations have required slab models of more than 30 monolayers of Sn to converge towards a bulk regime, where quantum confinement is no longer dominant.…”

Section: Introductionmentioning

confidence: 99%

First Principles Assessment of CdTe as a Tunnel Barrier at the $\mathbfα$-Sn/InSb Interface

Jardine¹,

Dardzinski²,

Yu³

et al. 2023

Preprint

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Majorana zero modes, with prospective applications in topological quantum computing, are expected to arise in superconductor/semiconductor interfaces, such as β-Sn and InSb. However, proximity to the superconductor may also adversely affect the semiconductor's local properties. A tunnel barrier inserted at the interface could resolve this issue. We assess the wide band gap semiconductor, CdTe, as a candidate material to mediate the coupling at the lattice-matched interface between α-Sn and InSb. To this end, we use density functional theory (DFT) with Hubbard U corrections, whose values are machine-learned via Bayesian optimization (BO) [npj Computational Materials 6, 180 (2020)]. The results of DFT+U(BO) are validated against angle resolved photoemission spectroscopy (ARPES) experiments for α-Sn and CdTe. For CdTe, the z-unfolding method [Advanced Quantum Technologies, 5, 2100033 (2022)] is used to resolve the contributions of different kz values to the ARPES. We then study the band offsets and the penetration depth of metal-induced gap states (MIGS) in bilayer interfaces of InSb/α-Sn, InSb/CdTe, and CdTe/α-Sn, as well as in tri-layer interfaces of InSb/CdTe/α-Sn with increasing thickness of CdTe. We find that 16 atomic layers (3.5 nm) of CdTe can serve as a tunnel barrier, effectively shielding the InSb from MIGS from the α-Sn. This may guide the choice of dimensions of the CdTe barrier to mediate the coupling in semiconductor-superconductor devices in future Majorana zero modes experiments.

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Best practices for first-principles simulations of epitaxial inorganic interfaces

Cited by 10 publications

References 309 publications

First Principles Study of the Electronic Structure of the Ni$_2$MnIn/InAs and Ti$_2$MnIn/InSb interfaces

First Principles Study of the Electronic Structure of the Ni$_2$MnIn/InAs and Ti$_2$MnIn/InSb interfaces

Scale-dependent optimized homoepitaxy of InAs(111)A

First Principles Assessment of CdTe as a Tunnel Barrier at the $\mathbfα$-Sn/InSb Interface

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