Berlin 2015 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 32: Transport: Topological Insulators 2 (jointly with DS, HL, MA, O)
TT 32.4: Talk
Tuesday, March 17, 2015, 10:15–10:30, H 3005
Tunnel Magnetoresistance scan of surface states of 3D topological insulators — •Sthitadhi Roy — Max-Planck-Institut für Physik komplexer Systeme, Dresden, Germany
The Fermi-surface of surface states of a 3D topological insulator (TI) has zero magnetization owing to time reversal symmetry, but an arbitrary segment of the full Fermi surface has a unique magnetic moment consistent with the type of spin-momentum locking. A three-terminal set up is proposed which directly couples to the magnetization of a chosen segment of a Fermi surface, hence leading to a finite tunnel magnetoresistance (TMR) response of the non-magnetic TI surface states, when coupled to spin polarized STM probe. This multi-terminal TMR reconstructs the in-plane momentum locked spin texture and also the out-of-plane spin polarization of hexagonally warped Fermi surfaces relevant for materials like Bi2Te3. This proposal is further extended to surfaces exposed by cleaving crystals at arbitrary angles to the crystal growth axis, and it shown that the TMR response not only probes and distinguishes these surfaces uniquely but the study of the spin textures for different surfaces put together acts like a hologram of the bulk band structure of the material.