T. M. Nenoff | Searcharxiv

arXiv2024

Time reversal symmetry breaking and zero magnetic field Josephson diode effect in Dirac semimetal Cd3As2-mediated asymmetric SQUIDs

A zero-magnetic-field Josephson diode effect (JDE) is observed in an asymmetric superconducting quantum interference device (SQUID) mediated by Dirac semimetal Cd3As2. We argue that a phase coupling between the surface and bulk superconducting channels, a unique phenomenon recently identified in the observations of fractional Josephson effect and Leggett modes in Cd3As2, can break time reversal symmetry and therefore give rise to the zero-field JDE. Our results are anticipated to have important implications in superconducting electronic circuit applications.

cond-mat.supr-con↗

arXiv2022

Evidence of decoupling of surface and bulk states in Dirac semimetal $Cd_{3}As_{2}$

Dirac semimetals have attracted a great deal of current interest due to their potential applications in topological quantum computing, low-energy electronic applications, and single photon detection in the microwave frequency range. Herein are results from analyzing the low magnetic (B) field weak-antilocalization behaviors in a Dirac semimetal $Cd_{3}As_{2}$ thin flake device. At high temperatures, the phase coherence length $l_ϕ$ first increases with decreasing temperature (T) and follows a power law dependence of $l_ϕ\propto$ T$^{-0.4}$. Below ~ 3K, $l_ϕ$ tends to saturate to a value of ~ 180 nm. Another fitting parameter $α$, which is associated with independence transport channels, displays a logarithmic temperature dependence for T > 3K, but also tends to saturate below ~ 3K. The saturation value, ~ 1.45, is very close to 1.5, indicating three independent electron transport channels, which we interpret as due to decoupling of both the top and bottom surfaces as well as the bulk. This result, to our knowledge, provides first evidence that the surfaces and bulk states can become decoupled in electronic transport in Dirac semimetal $Cd_{3}As_{2}$.

cond-mat.mes-hall↗