Suppression of transport spin-polarization of surface states with emergence of ferromagnetism in Mn-doped Bi2Se3

Abstract

The surface states of topological insulators (TI) are protected by time reversal symmetry and they display intrinsic spin helicity where the momentum of the charge carriers decides their spin states. As a consequence, a current injected through the surface states becomes spin polarized and this transport spin-polarization leads to a proportionate suppression of Andreev reflection in superconductor/TI junctions. Here we show that upon doping Bi2Se3 with Mn, the transport spin-polarization is seen to be monotonically suppressed. The parent compound Bi2Se3 is found to exhibit a transport spin-polarization of about 63% whereas crystals with 10% Mn doping show transport spin-polarization of about 48%. This suppression is accompanied by an increasing ferromagnetic order of the crystals with Mn doping. Scanning tunneling spectroscopy shows that the topological protection of the surface states reduce due to Mn doping. The net measured transport spin-polarization is due to a competition of this effect with the increased magnetization on Mn doping. The present results provide important insights for the choice of magnetic topological insulators for spintronic applications.

arXiv commentAccepted in Journal of Physics: Condensed Matter, 5 PAGES, 5 FIGURES

References in corpus (22)

• Topological Insulators
• Topological Insulators in Three Dimensions
• Experimental Observation of the Quantum Anomalous Hall Effect in a Magnetic Topological Insulator
• Topological Field Theory of Time-Reversal Invariant Insulators
• First observation of Spin-Momentum Helical Locking in Bi2Se3 and Bi2Te3, demonstration of Topological-Order at 300K and a realization of topological-transport-regime
• Magnetic impurities on the surface of a topological insulator
• Spin Polarization and Transport of Surface States in the Topological Insulators Bi2Se3 and Bi2Te3 from First Principles
• How to calculate the degree of spin polarization in ferromagnets?
• Landau Quantization of Massless Dirac Fermions in Topological Insulator
• Momentum-Resolved Landau-Level Spectroscopy of Dirac Surface State in Bi2Se3
• Electrically controllable surface magnetism on the surface of topological insulator
• Impurity-induced states on the surface of 3D topological insulators
• Probing Spin Polarization with Andreev Reflection: A Theoretical Basis
• The role of critical current on point contact Andreev Reflection spectrum between a normal metal and a superconductor
• Unconventional Superconductivity at Mesoscopic Point-contacts on the 3-Dimensional Dirac Semi-metal Cd${}_3$As${}_2$
• Electrical injection and detection of spin-polarized currents in topological insulator Bi2Te2Se
• Transport spin polarisation in SrRuO3 measured through Point Contact Andreev reflection
• Mapping the chemical potential dependence of current-induced spin polarization in a topological insulator
• RKKY Interaction On Surfaces of Topological Insulators With Superconducting Proximity Effect
• Temperature dependence of transport spin polarization in NdNi5 measured using Point Contact Andreev reflection
• Effect of Mn doping on ultrafast carrier dynamics in thin films of the topological insulator Bi2Se3
• Discovery of highly spin-polarized conducting surface states in the strong spin-orbit coupling semiconductor Sb${}_2$Se${}_3$

Cited by in corpus (4)

• High transport spin polarization in the van der Waals ferromagnet Fe${}_4$GeTe${}_2$
• Spin-orbit driven spin depolarization in the ferromagnetic Weyl semimetal Co3Sn2S2
• Spin-polarized supercurrent through the van der Waals Kondo lattice ferromagnet Fe${}_3$GeTe${}_2$
• High spin-polarization in the low Curie temperature complex itinerant ferromagnet EuTi${}_{1-x}$Nb${}_x$O${}_3$