Quasiparticle Interference around a Magnetic Impurity on a Surface with Strong Spin-Orbit Coupling

On surfaces with strong spin-orbit coupling, backscattering is forbidden since it requires flipping of the spin of the electron. It has been proposed that the forbidden scattering channels in such systems can be activated if time reversal symmetry is locally broken, for example, by a magnetic scattering center. Scanning tunneling spectroscopic maps of quasiparticle interference patterns around a single magnetic MnPc molecule on a Bi(110) surface reveal only spin-conserving scattering events. Simulations based on the Green's functions approach confirm that the charge-density interference patterns are unaffected by the magnetic state of the impurity. A fingerprint of backscattering processes appears, however, in the magnetization patterns, suggesting that only spin-polarized measurements can access this information.