Quantum-well states and magnetic coupling between ferromagnets through a noble-metal layer

Ortega, J. E.; Himpsel, F. J.; Mankey, G. J.; Willis, R. F.

doi:10.1103/physrevb.47.1540

Cited by 450 publications

(215 citation statements)

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“…Especially in noble metals, where disagreement is found with ground-state bands. 6,9 Here, we show that experiments and quasiparticle theory agree for Al and Cu films with unprecedented accuracy, demonstrating the validity of the thin-film approach. Such accuracy opens up a new way to explore correlation or electron-phonon coupling effects in the band structure near E F .…”

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confidence: 84%

“…4 Furthermore, if it is assumed that boundary conditions at the surface and the interface do not change by varying the film thickness, k Ќ (E) can be obtained directly from the so-called QW structure plot, i.e., the QW peak energy distribution as a function of film thickness. [5][6][7][8][9][10] Thus, the fundamental k Ќ uncertainty in bulk crystal photoemission is transferred to an experimentally, controllable thickness uncertainty in thin films.…”

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confidence: 99%

“…4 This leads to discrete quantum-well ͑QW͒ states in the photoemission spectra, with peaks at k Ќ (E) values that fulfill constructive interference conditions. [5][6][7][8][9][10] If the film is not too thin and the crystal structure is the same as in bulk materials, k Ќ (E) values actually sample bulk E(k) bands at discrete k Ќ points. 4 Furthermore, if it is assumed that boundary conditions at the surface and the interface do not change by varying the film thickness, k Ќ (E) can be obtained directly from the so-called QW structure plot, i.e., the QW peak energy distribution as a function of film thickness.…”

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confidence: 99%

“…Most of the data points lie below the absolute substrate band gap at ϳϪ0.5 eV, and hence they are resonances rather than pure quantum-well states, similar to those found in other systems like Cu films. 6 The thin lines fit simultaneously all data points using the expression…”

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confidence: 99%

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Accurate band mapping via photoemission from thin films

Mugarza¹,

Marini²,

Strasser

et al. 2004

Phys. Rev. B

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Electron bands in solids can be determined in angle-resolved photoemission experiments from thin films, where the perpendicular wave vector (k Ќ ) uncertainty that characterizes photoemission from bulk crystals is removed. However, the comparison with state-of-the-art quasiparticle band-structure calculations has never been done. In this work we have mapped both initial-state ͑occupied͒ and final-state ͑empty͒ E(k Ќ ) bands along the ⌳ axis of aluminum, from photon-energy-and thickness-dependent quantum-well spectra of aluminum films. For final states the best fit is obtained with inverse low-energy electron diffraction band structure calculations. For initial-state bands of Cu and Al, thin-film data display excellent agreement with bulk quasiparticle theory, suggesting the use of thin films as model systems to investigate fine effects in the crystal band structure. DOI: 10.1103/PhysRevB.69.115422 PACS number͑s͒: 73.20.Ϫr, 79.60.Bm An appropriate description of the electron band structures is of general interest as a fundamental property of crystalline solids that explains most of their observable behavior. Many different spectroscopic techniques probe electronic states, but only photoemission from well-defined crystal surfaces allows the thorough determination of E(k) band dispersions. 1 Angle-resolved, valence-band photoemission spectra are generally dominated by peaks that correspond to the so-called vertical transitions from initial to final bulk states, i.e., those where the wave vector k is conserved in the reduced Brillouin zone. The energy and the wave vector parallel to the surface can be determined with a high accuracy depending on the system resolution. However, the broken symmetry at the surface gives rise to a fundamental uncertainty that affects the perpendicular component of the wave vector k Ќ . Occupied bands are usually mapped assuming free-electron-like final-states to define k Ќ , but the actual final state band structure is often more complex as proved in constant initial-state ͑CIS͒ experiments. Such final states can be determined experimentally by very low-energy electron diffraction͑VLEED͒. 2,3 However, this method is limited to high-enough reflectivity, i.e., electron energies below 30 eV.The k Ќ uncertainty is removed in thin films, where k Ќ is fixed by thickness and boundary conditions at the surface interface. 4 This leads to discrete quantum-well ͑QW͒ states in the photoemission spectra, with peaks at k Ќ (E) values that fulfill constructive interference conditions. 5-10 If the film is not too thin and the crystal structure is the same as in bulk materials, k Ќ (E) values actually sample bulk E(k) bands at discrete k Ќ points. 4 Furthermore, if it is assumed that boundary conditions at the surface and the interface do not change by varying the film thickness, k Ќ (E) can be obtained directly from the so-called QW structure plot, i.e., the QW peak energy distribution as a function of film thickness. 5-10 Thus, the fundamental k Ќ uncertainty in bulk crystal photoemission is tran...

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confidence: 84%

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confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Accurate band mapping via photoemission from thin films

Mugarza¹,

Marini²,

Strasser

et al. 2004

Phys. Rev. B

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“…4,[6][7][8]10 As a consequence of the quantization of the electronic structure, many properties of metal films show a quantum size effect, [3][4][5][6]14,15 i.e., a (oscillatory) dependence on the film thickness D, where D can be changed only by the discrete amount given by the interlayer spacing a. Because of the fundamental and practical interest quantum size effects have been studied in detail for the work function and surface energy, [16][17][18][19][20] chemical reactivity, 21 magnetic coupling, 5,[22][23][24] Rashba effect, 25,26 etc.…”

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confidence: 99%

Quantum-well states with image state character for Pb overlayers on Cu(111)

et al. 2012

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We study theoretically the quantum well states (QWSs) localized in Pb overlayers on Cu(111) surface. Particular emphasis is given to the states with energies close to the vacuum level. Inclusion of the long-range image potential tail into the model potential description of the system allows us to show the effect of hybridization between QWSs and image potential states (ISs). The particle-in-a-box energy sequence characteristic for QWSs evolves into the Rydberg series converging towards the vacuum level. The electron density of the corresponding states is partially moved from inside the metal overlayer into the vacuum. The decay rates due to the inelastic electron-electron scattering decrease with increasing energy, opposite to "conventional" QWSs and similar to the ISs. Many-body and wave packet propagation calculations of the inelastic decay rates are supplemented by simple analysis based on the phase accumulation model and wave-function penetration approximation. This allows an analytical description of the dependence of the QWS/ISs hybridization on different parameters and, in particular, on the overlayer thickness.

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