Magnetoconductance Oscillations in Topological Crystalline Insulator Nanowires

Pb_1-xSn_xTe is a topological crystalline insulator (TCI) hosting topological surface and hinge states protected by crystal mirror symmetries. The bulk carrier density can be reduced by tuning the Sn ratio x. Here, we perform low-temperature magnetotransport measurements on Pb_1-xSn_xTe nanowires with varying x values grown by molecular beam epitaxy. We observe signatures of Aharonov-Bohm (AB)-type oscillations for 0.32 ≤ x ≤ 0.51, which coexist with aperiodic universal conductance fluctuations (UCFs) and are consistent with phase-coherent transport on the nanowire surface. We separately analyze the temperature dependence of the AB-type oscillations and UCFs. The oscillations give a phase coherence length of l_ϕ = 1.4 ± 0.2 μm at 80 mK, consistent with the ballistic transport regime. The UCF provides a significantly smaller l_ϕ, consistent with a diffusive bulk transport channel, parallel to the ballistic surface. Our results indicate the presence of phase-coherent surface states on Pb_1-xSn_xTe nanowires with 0.32 ≤ x ≤ 0.51.