Electronic Properties of High-Quality Epitaxial Topological Dirac Semimetal Thin Films.
Topological Dirac semimetals (TDS) are three-dimensional analogues of graphene, with linear electronic dispersions in three dimensions. Nanoscale confinement of TDSs in thin films is a necessary step toward observing the conventional-to-topological quantum phase transition (QPT) with increasing film thickness, gated devices for electric-field control of topological states, and devices with surface-state-dominated transport phenomena. Thin films can also be interfaced with superconductors (realizing a host for Majorana Fermions) or ferromagnets (realizing Weyl Fermions or T-broken topological states). Here we report structural and electrical characterization of large-area epitaxial thin films of TDS Na3Bi on single crystal Al2O3[0001] substrates. Charge carrier mobilities exceeding 6,000 cm(2)/(V s) and carrier densities below 1 × 10(18) cm(-3) are comparable to the best single crystal values. Perpendicular magnetoresistance at low field shows the perfect weak antilocalization behavior expected for Dirac Fermions in the absence of intervalley scattering. At higher fields up to 0.5 T anomalously large quadratic magnetoresistance is observed, indicating that some aspects of the low field magnetotransport (μB < 1) in this TDS are yet to be explained.
School of Physics and Astronomy and Monash Centre for Atomically Thin Materials, Monash University , Victoria 3800, Australia.
Jack
J
Hellerstedt
School of Physics and Astronomy and Monash Centre for Atomically Thin Materials, Monash University , Victoria 3800, Australia.
Mark T
MT
Edmonds
Department of Physics and Centre for Advanced 2D Materials, National University of Singapore , 117551, Singapore.
Navneeth
N
Ramakrishnan
School of Physics and Astronomy and Monash Centre for Atomically Thin Materials, Monash University , Victoria 3800, Australia.
Chang
C
Liu
School of Physics and Astronomy and Monash Centre for Atomically Thin Materials, Monash University , Victoria 3800, Australia.
Bent
B
Weber
Australian Synchrotron, Clayton, Victoria 3168, Australia.
Anton
A
Tadich
Curtin University , Perth, Western Australia 6102, Australia.
Kane M
KM
O'Donnell
Department of Physics and Centre for Advanced 2D Materials, National University of Singapore , 117551, Singapore.|Yale-NUS College , 6 College Avenue East, 138614, Singapore.
Shaffique
S
Adam
School of Physics and Astronomy and Monash Centre for Atomically Thin Materials, Monash University , Victoria 3800, Australia.
Michael S
MS
Fuhrer
Topological Dirac semimetal; magnetotransport; scanning tunneling microscopy; thin film growth