Coherent Epitaxial Semiconductor–Ferromagnetic Insulator InAs/EuS Interfaces: Band Alignment and Magnetic Structure

Liu, Yu; Luchini, Alessandra; Martí‐Sánchez, Sara; Koch, Christian; Schuwalow, Sergej; Khan, Sabbir Ahmed; Stankevič, Tomaš; Francoual, S.; Mardegan, J. R. L.; Krieger, Jonas A.; Strocov, Vladimir N.; Stahn, J.; Vaz, C. A. F.; Ramakrishnan, Mahesh; Staub, U.; Lefmann, Kim; Aeppli, G.; Arbiol, Jordi; Krogstrup, Peter

doi:10.1021/acsami.9b15034

Cited by 38 publications

(51 citation statements)

References 73 publications

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“…[ 52 ] The effective Hubbard parameter

U^{*} = U - J = 5

eV was chosen to ensure the binding energy of Eu 4f states to be in agreement with available photoemission experiments. [ 53,54 ] To verify the value of

U^{*}

, we calculated various magnetic properties of EuS bulk. The obtained magnetic moment

μ_{Eu}^{theory} = 6.93 {normalμ}_{normalB}

and the Curie temperature

T_{normalC}^{theory} = 15.3 K

are in good agreement with experimental results,

μ_{Eu}^{exp} \approx 7 {normalμ}_{normalB}

and

T_{normalC}^{exp} = 16.3 K

, respectively.…”

Section: Ab Initio Calculationsmentioning

confidence: 99%

Structure and Magnetism of EuS on Bi₂Se₃(0001)

Meyerheim

Ernst

Mohseni

et al. 2020

Physica Status Solidi (b)

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The rocksalt‐type ferromagnetic (FM) insulator EuS (bulk TC = 17 K) grown on Bi2Se3 with well‐matched (111) plane of the film and (0001) plane of the substrate is studied. The system may feature magnetic proximity effect breaking the time‐reversal symmetry and opening a bandgap in the metallic topologically protected surface state of Bi2Se3. The experimental X‐ray diffraction studies are combined with ab initio calculations to resolve contradictory results concerning the enhancement of the TC up to 300 K and the degree of induced magnetization in the system. It is concluded that previous studies relied on idealized and unconfirmed structure models. Herein, it is shown by surface X‐ray diffraction (SXRD) with ab initio calculations that a two double layer‐thick EuS film grows with a sharp interface and without chemical intermixing in a single domain state in an FCC‐type stacking on the Bi2Se3(0001) surface in which the topmost layer is metallic, thereby lifting polarity. A large pz‐orbital‐derived top‐layer sulfur magnetic moment of 0.6 μB is found, whereas for europium, μEu = 6.9 μB throughout the film is found. No magnetization within the first Bi2Se3 quintuple layer is found. The calculation of the exchange parameters Jij indicates a complex FM and antiferromagnetic ordering between europium and sulfur with a maximum Néel temperature of 226 K.

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“…[ 52 ] The effective Hubbard parameter

U^{*} = U - J = 5

eV was chosen to ensure the binding energy of Eu 4f states to be in agreement with available photoemission experiments. [ 53,54 ] To verify the value of

U^{*}

, we calculated various magnetic properties of EuS bulk. The obtained magnetic moment

μ_{Eu}^{theory} = 6.93 {normalμ}_{normalB}

and the Curie temperature

T_{normalC}^{theory} = 15.3 K

are in good agreement with experimental results,

μ_{Eu}^{exp} \approx 7 {normalμ}_{normalB}

and

T_{normalC}^{exp} = 16.3 K

, respectively.…”

Section: Ab Initio Calculationsmentioning

confidence: 99%

Structure and Magnetism of EuS on Bi₂Se₃(0001)

Meyerheim

Ernst

Mohseni

et al. 2020

Physica Status Solidi (b)

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“…In Ref. [21] a defect-free heterostructure between an InAs semiconductor wire and EuS has been prepared and studied. Negligible direct magnetization of InAs was reported.…”

Section: Introductionmentioning

confidence: 99%

Topological superconductivity in nanowires proximate to a diffusive superconductor–magnetic-insulator bilayer

et al. 2021

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We study semiconductor nanowires coupled to a bilayer of a disordered superconductor and a magnetic insulator, motivated by recent experiments reporting possible Majorana-zero-mode signatures in related architectures. Specifically, we pursue a quasiclassical Usadel equation approach that treats superconductivity in the bilayer self-consistently in the presence of spin-orbit scattering, magnetic-impurity scattering, and Zeeman splitting induced by both the magnetic insulator and a supplemental applied field. Within this framework we explore prospects for engineering topological superconductivity in a nanowire proximate to the bilayer. We find that a magnetic-insulator-induced Zeeman splitting, mediated through the superconductor alone, cannot induce a topological phase since the destruction of superconductivity (i.e., Clogston limit) preempts the required regime in which the nanowire's Zeeman energy exceeds the induced pairing strength. However, this Zeeman splitting does reduce the critical applied field needed to access the topological phase transition, with fields antiparallel to the magnetization of the magnetic insulator having an optimal effect. Finally, we show that magnetic-impurity scattering degrades the topological phase, and spin-orbit scattering, if present in the superconductor, pushes the Clogston limit to higher fields yet simultaneously increases the critical applied field strength.

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“…Partly-overlapping, two-faceted EuS (as grown thickness 8 nm) and Al (as grown thickness 6 nm) shells were grown in situ using electron beam evaporation, as shown in the maintext Fig. 1(a) [28,39]. Devices were fabricated on a Si substrate with 200 nm SiOx capping.…”

Section: Supplementary Materials Sample Preparationmentioning

confidence: 99%

Evidence for spin-polarized bound states in semiconductor-superconductor-ferromagnetic insulator islands

Vaitiekėnas,

Souto,

Liu

et al. 2021

Preprint

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We report Coulomb blockade transport studies of InAs nanowires grown with epitaxial superconducting Al and ferromagnetic insulator EuS on overlapping facets. By comparing experimental results to a theoretical model, we associate cotunneling features in even-odd bias spectra with spinpolarized Andreev levels, indicating that spin splitting exceeding the induced superconducting gap at zero applied magnetic field. Energies of the polarized subgap states can be tuned on either side of zero by electrostatic gates.

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Coherent Epitaxial Semiconductor–Ferromagnetic Insulator InAs/EuS Interfaces: Band Alignment and Magnetic Structure

Cited by 38 publications

References 73 publications

Structure and Magnetism of EuS on Bi₂Se₃(0001)

Structure and Magnetism of EuS on Bi₂Se₃(0001)

Topological superconductivity in nanowires proximate to a diffusive superconductor–magnetic-insulator bilayer

Evidence for spin-polarized bound states in semiconductor-superconductor-ferromagnetic insulator islands

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Coherent Epitaxial Semiconductor–Ferromagnetic Insulator InAs/EuS Interfaces: Band Alignment and Magnetic Structure

Cited by 38 publications

References 73 publications

Structure and Magnetism of EuS on Bi2Se3(0001)

Structure and Magnetism of EuS on Bi2Se3(0001)

Topological superconductivity in nanowires proximate to a diffusive superconductor–magnetic-insulator bilayer

Evidence for spin-polarized bound states in semiconductor-superconductor-ferromagnetic insulator islands

Contact Info

Product

Resources

About

Structure and Magnetism of EuS on Bi₂Se₃(0001)

Structure and Magnetism of EuS on Bi₂Se₃(0001)