Phase-coherent transport in catalyst-free vapor phase deposited Bi2Se3 crystals

Abstract

Freestanding Bi2Se3 single-crystal flakes of variable thicknesses are grown using a catalyst-free vapor-solid synthesis and are subsequently transferred onto a clean Si++/SiO2 substrate where the flakes are contacted in Hall bar geometry. Low-temperature magnetoresistance measurements are presented which show a linear magnetoresistance for high magnetic fields and weak antilocalization (WAL) at low fields. Despite an overall strong charge-carrier tunability for thinner devices, we find that electron transport is dominated by bulk contributions for all devices. Phase-coherence lengths l(phi) as extracted from WAL measurements increase linearly with increasing electron density exceeding 1 mu m at 1.7 K. Although l(phi) is in qualitative agreement with electron-electron interaction-induced dephasing, we find that spin-flip scattering processes limit l(phi) at low temperatures.