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Experimental Methods for Spin- and Angle-Resolved Photoemission Spectroscopy Combined with Polarization-Variable Laser
Published on: June 28, 2018
Quasiparticle interference around a magnetic impurity on a surface with strong spin-orbit coupling.
Anna Stróżecka1, Asier Eiguren, Jose Ignacio Pascual
1Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, D14195 Berlin, Germany.
Physical Review Letters
|November 24, 2011
Summary
Forbidden electron backscattering on spin-orbit coupled surfaces can be activated by breaking time reversal symmetry. However, experiments show only spin-conserving events in charge density, with backscattering appearing in magnetization patterns, requiring spin-polarized measurements.
Area of Science:
- Condensed matter physics
- Surface science
- Quantum mechanics
Background:
- Strong spin-orbit coupling on surfaces forbids electron backscattering due to spin conservation.
- Breaking time reversal symmetry, e.g., with magnetic impurities, may enable forbidden scattering channels.
Purpose of the Study:
- Investigate quasiparticle interference patterns around a magnetic impurity on a surface with strong spin-orbit coupling.
- Determine if magnetic impurities activate forbidden spin-flipping backscattering channels.
- Explore the role of spin conservation and time reversal symmetry in scattering processes.
Main Methods:
- Scanning tunneling spectroscopy (STS) to map quasiparticle interference patterns.
- Utilizing a single magnetic manganese phthalocyanine (MnPc) molecule on a bismuth (Bi) surface.
- Simulations using the Green's functions approach to model charge-density and magnetization patterns.
Main Results:
- STS maps revealed only spin-conserving scattering events around the MnPc molecule.
- Simulations confirmed that charge-density interference patterns are independent of the impurity's magnetic state.
- Backscattering signatures were observed in magnetization patterns, not charge density.
Conclusions:
- Charge-density interference measurements are insufficient to detect spin-flipping backscattering.
- Local breaking of time reversal symmetry by a magnetic impurity does not activate backscattering in charge density.
- Spin-polarized measurements are necessary to observe signatures of forbidden backscattering processes.
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