Quantized Ballistic Transport of Electrons and Electron Pairs in LaAlO3/SrTiO3 Nanowires

• Published in: Nano letters 2018-07, Vol.18 (7), p.4473-4481
• Main Authors: Annadi, Anil, Cheng, Guanglei, Lee, Hyungwoo, Lee, Jung-Woo, Lu, Shicheng, Tylan-Tyler, Anthony, Briggeman, Megan, Tomczyk, Michelle, Huang, Mengchen, Pekker, David, Eom, Chang-Beom, Irvin, Patrick, Levy, Jeremy
• Format: Article
• Language: English
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/acs.nanolett.8b01614

SrTiO3-based heterointerfaces support quasi-two-dimensional (2D) electron systems that are analogous to III–V semiconductor heterostructures, but also possess superconducting, magnetic, spintronic, ferroelectric, and ferroelastic degrees of freedom. Despite these rich properties, the relatively low mobilities of 2D complex-oxide interfaces appear to preclude ballistic transport in 1D. Here we show that the 2D LaAlO3/SrTiO3 interface can support quantized ballistic transport of electrons and (nonsuperconducting) electron pairs within quasi-1D structures that are created using a well-established conductive atomic-force microscope (c-AFM) lithography technique. The nature of transport ranges from truly single-mode (1D) to three-dimensional (3D), depending on the applied magnetic field and gate voltage. Quantization of the lowest e 2/h plateau indicate a ballistic mean-free path l MF ∼ 20 μm, more than 2 orders of magnitude larger than for 2D LaAlO3/SrTiO3 heterostructures. Nonsuperconducting electron pairs are found to be stable in magnetic fields as high as B = 11 T and propagate ballistically with conductance quantized at 2e 2/h. Theories of one-dimensional (1D) transport of interacting electron systems depend crucially on the sign of the electron–electron interaction, which may help explain the highly ballistic transport behavior. The 1D geometry yields new insights into the electronic structure of the LaAlO3/SrTiO3 system and offers a new platform for the study of strongly interacting 1D electronic systems.