Large zero bias peaks and dips in a four-terminal thin InAs-Al nanowire device

Abstract

We report electron transport studies of a thin InAs-Al hybrid semiconductor-superconductor nanowire device using a four-terminal design. Compared to previous works, thinner InAs nanowire (diameter less than 40 nm) is expected to reach fewer sub-band regime. The four-terminal device design excludes electrode contact resistance, an unknown value which has inevitably affected previously reported device conductance. Using tunneling spectroscopy, we find large zero-bias peaks (ZBPs) in differential conductance on the order of 2e 2 /h. Investigating the ZBP evolution by sweeping various gate voltages and magnetic field, we find a transition between a zero-bias peak and a zero-bias dip while the zero-bias conductance sticks close to 2e 2 /h. We discuss a topologically trivial interpretation involving disorder, smooth potential variation and quasi-Majorana zero modes.

Suppressing Andreev bound state zero bias peaks using a strongly dissipative lead

“…Probing MZMs with a regular normal lead reveals zero-bias peaks (ZBPs) in tunneling conductance. The quantitative behavior of the ZBPs observed in experiments [21][22][23][24][25][26], however, does not fully follow the simplest MZM theory's prediction. For example, the perfect Majorana quantization [27,28] has not been observed yet.…”

Non-Hermiticity stabilized Majorana zero modes in semiconductor-superconductor nanowires

“…Although the formula indicates the presence of a quantized zero bias peak (ZBP) 2e 2 /h for Γ 1 Γ 2 E 2 M , the ZBP in experiment may oscillate around 2e 2 /h, because E M changes with µ. Such fluctuation may explain the instability of quantized ZBP observed in recent experiments [53,54,68,69].…”

“…These quasi-MZMs are actually a pair of coupled MZMs separated by a finite distance, and their nonzero energies can lead to undesirable dynamic phase in their time-evolution, making them inappropriate for topological quantum computation (TQC). Eliminating the influence of quasi-MZMs and distinguishing them from real ones thus become important tasks in Majorana physics [30][31][32][33][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54].…”

Observation of Aharonov-Bohm effect in PbTe nanowire networks

“…One-dimensional semiconductor-superconductor hybrid nanowire is a promising MZM candidate [7][8][9][10] where the phase coherent transport can be revealed as Aharonov-Bohm (AB) oscillations in nanowire networks with a loop geometry. Among all 1D candidates, InSb and InAs nanowires are the mostly studied MZM material systems [11][12][13][14][15][16], with AB effect demonstrated [17][18][19][20][21]. Recently, PbTe [22][23][24][25][26][27] based nanowires [28,29] have been proposed as a new MZM candidate [30].…”