Magneto-transport Studies of Topological Insulators and Spintronic Nano-devices

 

The magneto-resistance (MR) of a condensed matter system provides useful information

about the Fermi surface and interactions, and can sometimes offer great opportunities in

magnetic sensor and memory applications. In the first part of my talk, I will present the

MR studies of a new class of quantum materials called 3-d topological insulators that

have unique topological surface states protected by time-reversal symmetry. A nonsaturating

linear-like MR was observed up to a magnetic field of 60 Tesla in epitaxial

thin films of topological insulator Bi2Te3. The possible origins of this linear-like MR,

including quantum quantization of Dirac Fermions, sample inhomogeneity and weak

anti-localization effect, will be discussed. In the second part, I will present the electrical

injection and detection of spin-polarized current in quasi-one dimensional silicon

nanowires. In particular, I will show the non-local spin valve effect in Co/AlOx/Si

nanowire devices and discuss the influence of temperature, bias current and contact

geometry on the spin-valve signal.