Exchange-split interface state at h-BN/Ni(111)

Zumbrägel, K.; Wulff, K.; Eibl, Christian; Donath, M.; Hengsberger, Matthias

doi:10.1103/physrevb.78.085422

Cited by 8 publications

(25 citation statements)

References 42 publications

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“…The ferromagnetic exchange splitting of the Ni 3d bands lifts the spin degeneracy of both the IPS and the interface state. sr-IPE locates the majority band bottom of the interface state at 1.7 eV above E F and gives a value of 150 meV for the exchange splitting, 13 in excellent agreement with DFT. 22 The absence of a photohole in the case of IPE might explain that the binding energy obtained from 2PPE data is lower by 190 meV than the results of IPE.…”

Section: Spectroscopysupporting

confidence: 67%

“…Complementary information about the unoccupied band structure has been obtained by means of spin-resolved inverse photoemission (sr-IPE). 13 Two distinct intermediate states between the Fermi level and the vacuum level have been detected in 2PPE, both populated by excitation from the 3d bands of Ni(111). One of these intermediate states is the n = 1 image potential state (IPS) of the nickel substrate with a remarkably long lifetime of 261 fs; the other one is a h-BN-derived interlayer or interface state with a lifetime of 107 fs.…”

Section: Introductionmentioning

confidence: 98%

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Disentanglement of electron dynamics and space-charge effects in time-resolved photoemission fromh-BN/Ni(111)

et al. 2011

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We observe time-resolved and polarization dependent two-, three-, and four-photon transitions from a Ni(111) surface covered with a monolayer of hexagonal boron nitride. The spectra show features due to transitions involving two unoccupied intermediate states: the n = 1 image potential state of Ni(111) and a boron nitriderelated interface state. We use these transitions in order to track the effects of space-charge on the spectra in view of pump-probe experiments, at high excitations densities. A simple model is presented, which reproduces the measured energy shifts and broadenings in great detail, allowing the ultrafast dynamics and the space-charge effects to be disentangled. Moreover, owing to the high excitation densities an additional particular three-photon transition via both the interface state and a virtual intermediate state could be measured and identified. The polarization-dependent transient of this transition has successfully been simulated, allowing the lifetime of the involved intermediate state to be extracted from the data.

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Section: Spectroscopysupporting

confidence: 67%

Section: Introductionmentioning

confidence: 98%

Disentanglement of electron dynamics and space-charge effects in time-resolved photoemission fromh-BN/Ni(111)

et al. 2011

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“…For the isolated layer and with many-body corrections included, the interlayer state becomes the lowest unoccupied state at Γ. This was confirmed by calculations for adsorbed and isolated layers [102] and experiments [92] as we will see in the following. Thus, in this limit the gap is indirect as well.…”

Section: Nearly-free-electron Interlayer States In H-bnsupporting

confidence: 75%

“…Moreover, spin-resolved spectra can be taken at the COPHEE endstation of the Swiss Light Source [91]. The inverse photoemission data were taken at the University of Münster (Germany) by the group of M. Donath [92], and their experimental setup is described in detail elsewhere [93].…”

Section: Experimental Setup For (Time-resolved) Photoelectron Spectroscopymentioning

confidence: 99%

Dynamics of excited interlayer states in hexagonal boron nitride monolayers

Hengsberger¹,

Leuenberger²,

Schuler³

et al. 2020

J. Phys. D: Appl. Phys.

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Hexagonal boron nitride () is the isoelectronic but insulating counterpart of graphene. Like graphene it can easily be grown as high-quality nanotubes or as single layers on metal surfaces. Both materials can be exfoliated or transferred after single-layer growth from suitable substrates onto new surfaces. In view of electronic devices or optical sensors, for instance, the carrier dynamics in the conduction bands determine the device properties. The band edge of the unoccupied band structure of is dominated by two kinds of states, free-electron-like interlayer or interface states and a flat conduction band valley derived from -states. The measurement of excited states and excited-state lifetimes in is the main topic of the present article with a special focus on the dynamics close to the -point. While the conduction band minimum is strongly localised at the boron sites, the charge density of free-electron-like states is outside the planes and is likely to be important for interactions like charge transfer with adjacent layers and substrates. We will review previous efforts to determine the nature of the bandgap and the band structure of unoccupied states with particular emphasis on but not restricted to single-layer epitaxially grown on a Ni(1 1 1) surface.

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“…This is because only s or p electrons contributing to the magnetic signal in layered h-BN directly challenges the conventional condensed magnetic phases of 3d or 4f transition metals. At present, a number of factors are thought to possibly give rise to the magnetic state in h-BN systems: defects in the atomic network, [24][25][26][27][28][29] ferromagnetic substrates induced magnetism, [30][31][32] and bared edge localized states. [33][34][35] Among these factors the defect-mediated mechanism appears to be a difficult one because negatively curved regions can hardly be found in layered h-BN, which is not the focus of this paper.…”

Section: Introductionmentioning

confidence: 99%

Intrinsic ferromagnetism in hexagonal boron nitride nanosheets

Gao

Yang

et al. 2014

The Journal of Chemical Physics

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Understanding the mechanism of ferromagnetism in hexagonal boron nitride nanosheets, which possess only s and p electrons in comparison with normal ferromagnets based on localized d or f electrons, is a current challenge. In this work, we report an experimental finding that the ferromagnetic coupling is an intrinsic property of hexagonal boron nitride nanosheets, which has never been reported before. Moreover, we further confirm it from ab initio calculations. We show that the measured ferromagnetism should be attributed to the localized π states at edges, where the electron-electron interaction plays the role in this ferromagnetic ordering. More importantly, we demonstrate such edge-induced ferromagnetism causes a high Curie temperature well above room temperature. Our systematical work, including experimental measurements and theoretical confirmation, proves that such unusual room temperature ferromagnetism in hexagonal boron nitride nanosheets is edge-dependent, similar to widely reported graphene-based materials. It is believed that this work will open new perspectives for hexagonal boron nitride spintronic devices.

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Exchange-split interface state at h-BN/Ni(111)

Cited by 8 publications

References 42 publications

Disentanglement of electron dynamics and space-charge effects in time-resolved photoemission fromh-BN/Ni(111)

Disentanglement of electron dynamics and space-charge effects in time-resolved photoemission fromh-BN/Ni(111)

Dynamics of excited interlayer states in hexagonal boron nitride monolayers

Intrinsic ferromagnetism in hexagonal boron nitride nanosheets

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