Limits...
Hierarchical spin-orbital polarization of a giant Rashba system.

Bawden L, Riley JM, Kim CH, Sankar R, Monkman EJ, Shai DE, Wei HI, Lochocki EB, Wells JW, Meevasana W, Kim TK, Hoesch M, Ohtsubo Y, Le Fèvre P, Fennie CJ, Shen KM, Chou F, King PD - Sci Adv (2015)

Bottom Line: The Rashba effect is one of the most striking manifestations of spin-orbit coupling in solids and provides a cornerstone for the burgeoning field of semiconductor spintronics.Combining polarization-dependent and resonant angle-resolved photoemission measurements with density functional theory calculations, we show that the two "spin-split" branches of the model giant Rashba system BiTeI additionally develop disparate orbital textures, each of which is coupled to a distinct spin configuration.This necessitates a reinterpretation of spin splitting in Rashba-like systems and opens new possibilities for controlling spin polarization through the orbital sector.

View Article: PubMed Central - PubMed

Affiliation: SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews, Fife KY16 9SS, UK.

ABSTRACT
The Rashba effect is one of the most striking manifestations of spin-orbit coupling in solids and provides a cornerstone for the burgeoning field of semiconductor spintronics. It is typically assumed to manifest as a momentum-dependent splitting of a single initially spin-degenerate band into two branches with opposite spin polarization. Combining polarization-dependent and resonant angle-resolved photoemission measurements with density functional theory calculations, we show that the two "spin-split" branches of the model giant Rashba system BiTeI additionally develop disparate orbital textures, each of which is coupled to a distinct spin configuration. This necessitates a reinterpretation of spin splitting in Rashba-like systems and opens new possibilities for controlling spin polarization through the orbital sector.

No MeSH data available.


Related in: MedlinePlus

Mapping the angle-dependent orbital wave functions.(A) Angular distribution of the Bi py-projected spectral weight distribution measured on-resonance around the inner band of CESs (see, for example, Fig. 3B), each normalized to its average value. Above (below) the Dirac point, ED, this is peaked at an azimuthal angle of α = π/2 (0 and π) indicative of a tangential (radial) in-plane orbital alignment. (B) The smooth evolution between these two configurations is captured by the relative spectral weight ADF, λ(ω) = [Iα=π/2(ω) − Iα=0,π(ω)]/[Iα=π/2(ω) + Iα=0,π(ω)], which crosses zero at the Dirac point within our experimental error. (C) This behavior is fully captured by the momentum-dependent Bi py:px in-plane orbital polarization, ζ(ω, k), extracted from our density functional theory (DFT) calculations. (D) The in-plane orbital polarization is reversed for the Te-projected component, with radial alignment above the Dirac point and tangential alignment below ED, as also captured by the opposite ADF measured off-resonance (hν = 30 eV; see Fig. 3C, summarized in B).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4643772&req=5

Figure 4: Mapping the angle-dependent orbital wave functions.(A) Angular distribution of the Bi py-projected spectral weight distribution measured on-resonance around the inner band of CESs (see, for example, Fig. 3B), each normalized to its average value. Above (below) the Dirac point, ED, this is peaked at an azimuthal angle of α = π/2 (0 and π) indicative of a tangential (radial) in-plane orbital alignment. (B) The smooth evolution between these two configurations is captured by the relative spectral weight ADF, λ(ω) = [Iα=π/2(ω) − Iα=0,π(ω)]/[Iα=π/2(ω) + Iα=0,π(ω)], which crosses zero at the Dirac point within our experimental error. (C) This behavior is fully captured by the momentum-dependent Bi py:px in-plane orbital polarization, ζ(ω, k), extracted from our density functional theory (DFT) calculations. (D) The in-plane orbital polarization is reversed for the Te-projected component, with radial alignment above the Dirac point and tangential alignment below ED, as also captured by the opposite ADF measured off-resonance (hν = 30 eV; see Fig. 3C, summarized in B).

Mentions: A similar conclusion can be drawn for the inner band of the CES at energies below the Dirac point formed by the crossing of the two spin-split branches of the dispersion. As already evident 100 meV below the Dirac point in Fig. 3 (B and C), and more clearly shown in the angular dependence of spectral weight extracted around the CES in Fig. 4A, the spectral weight still peaks along the ky direction (α = 0 and π in Fig. 4A), with a suppression of spectral weight along kx (α = π/2). Indeed, whereas the band edge turning point in the dispersion leads to a van Hove singularity in the density of states (23), the inner band of the CES below the Dirac point smoothly evolves into the outer band as it moves through this turning point, and thus hosts qualitatively the same orbital texture.


Hierarchical spin-orbital polarization of a giant Rashba system.

Bawden L, Riley JM, Kim CH, Sankar R, Monkman EJ, Shai DE, Wei HI, Lochocki EB, Wells JW, Meevasana W, Kim TK, Hoesch M, Ohtsubo Y, Le Fèvre P, Fennie CJ, Shen KM, Chou F, King PD - Sci Adv (2015)

Mapping the angle-dependent orbital wave functions.(A) Angular distribution of the Bi py-projected spectral weight distribution measured on-resonance around the inner band of CESs (see, for example, Fig. 3B), each normalized to its average value. Above (below) the Dirac point, ED, this is peaked at an azimuthal angle of α = π/2 (0 and π) indicative of a tangential (radial) in-plane orbital alignment. (B) The smooth evolution between these two configurations is captured by the relative spectral weight ADF, λ(ω) = [Iα=π/2(ω) − Iα=0,π(ω)]/[Iα=π/2(ω) + Iα=0,π(ω)], which crosses zero at the Dirac point within our experimental error. (C) This behavior is fully captured by the momentum-dependent Bi py:px in-plane orbital polarization, ζ(ω, k), extracted from our density functional theory (DFT) calculations. (D) The in-plane orbital polarization is reversed for the Te-projected component, with radial alignment above the Dirac point and tangential alignment below ED, as also captured by the opposite ADF measured off-resonance (hν = 30 eV; see Fig. 3C, summarized in B).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4643772&req=5

Figure 4: Mapping the angle-dependent orbital wave functions.(A) Angular distribution of the Bi py-projected spectral weight distribution measured on-resonance around the inner band of CESs (see, for example, Fig. 3B), each normalized to its average value. Above (below) the Dirac point, ED, this is peaked at an azimuthal angle of α = π/2 (0 and π) indicative of a tangential (radial) in-plane orbital alignment. (B) The smooth evolution between these two configurations is captured by the relative spectral weight ADF, λ(ω) = [Iα=π/2(ω) − Iα=0,π(ω)]/[Iα=π/2(ω) + Iα=0,π(ω)], which crosses zero at the Dirac point within our experimental error. (C) This behavior is fully captured by the momentum-dependent Bi py:px in-plane orbital polarization, ζ(ω, k), extracted from our density functional theory (DFT) calculations. (D) The in-plane orbital polarization is reversed for the Te-projected component, with radial alignment above the Dirac point and tangential alignment below ED, as also captured by the opposite ADF measured off-resonance (hν = 30 eV; see Fig. 3C, summarized in B).
Mentions: A similar conclusion can be drawn for the inner band of the CES at energies below the Dirac point formed by the crossing of the two spin-split branches of the dispersion. As already evident 100 meV below the Dirac point in Fig. 3 (B and C), and more clearly shown in the angular dependence of spectral weight extracted around the CES in Fig. 4A, the spectral weight still peaks along the ky direction (α = 0 and π in Fig. 4A), with a suppression of spectral weight along kx (α = π/2). Indeed, whereas the band edge turning point in the dispersion leads to a van Hove singularity in the density of states (23), the inner band of the CES below the Dirac point smoothly evolves into the outer band as it moves through this turning point, and thus hosts qualitatively the same orbital texture.

Bottom Line: The Rashba effect is one of the most striking manifestations of spin-orbit coupling in solids and provides a cornerstone for the burgeoning field of semiconductor spintronics.Combining polarization-dependent and resonant angle-resolved photoemission measurements with density functional theory calculations, we show that the two "spin-split" branches of the model giant Rashba system BiTeI additionally develop disparate orbital textures, each of which is coupled to a distinct spin configuration.This necessitates a reinterpretation of spin splitting in Rashba-like systems and opens new possibilities for controlling spin polarization through the orbital sector.

View Article: PubMed Central - PubMed

Affiliation: SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews, Fife KY16 9SS, UK.

ABSTRACT
The Rashba effect is one of the most striking manifestations of spin-orbit coupling in solids and provides a cornerstone for the burgeoning field of semiconductor spintronics. It is typically assumed to manifest as a momentum-dependent splitting of a single initially spin-degenerate band into two branches with opposite spin polarization. Combining polarization-dependent and resonant angle-resolved photoemission measurements with density functional theory calculations, we show that the two "spin-split" branches of the model giant Rashba system BiTeI additionally develop disparate orbital textures, each of which is coupled to a distinct spin configuration. This necessitates a reinterpretation of spin splitting in Rashba-like systems and opens new possibilities for controlling spin polarization through the orbital sector.

No MeSH data available.


Related in: MedlinePlus