Babich Ian, Kudriashov Andrei, Baranov Denis, Stolyarov Vasily S
Advanced Mesoscience and Nanotechnology Centre, Moscow Institute of Physics and Technology, 141700, Dolgoprudny, Russia.
National University of Science and Technology MISIS, 119049 Moscow, Russia.
Nano Lett. 2023 Jul 26;23(14):6713-6719. doi: 10.1021/acs.nanolett.3c01970. Epub 2023 Jul 10.
Exotic quantum transport phenomena established in Josephson junctions (JJs) are reflected by a nonsinusoidal current-phase relation (CPR). The solidified approach to measuring the CPR is via an asymmetric dc-SQUID with a reference JJ that has a high critical current. We probed this method by measuring CPRs of hybrid JJs based on the 3D topological insulator (TI) BiTeSe with a nanobridge acting as a reference JJ. We captured both highly skewed and sinusoidal critical current oscillations within single devices which contradict the uniqueness of the CPR. This implies that the widely used method provides inaccurate CPR measurement and leads to misinterpretation. It was shown that the accuracy of the CPR measurement is mediated by the asymmetry in derivatives of the CPRs but not in critical currents, as was previously thought. Finally, we provided considerations for an accurate CPR measurement via the most commonly used reference JJs.
约瑟夫森结（JJs）中建立的奇异量子输运现象通过非正弦电流-相位关系（CPR）得以体现。测量CPR的传统方法是通过一个带有高临界电流参考结的非对称直流超导量子干涉器件（dc-SQUID）。我们通过测量基于三维拓扑绝缘体（TI）BiTeSe且具有纳米桥作为参考结的混合结的CPR来探究此方法。我们在单个器件中捕获到了高度不对称和正弦形的临界电流振荡，这与CPR的唯一性相矛盾。这意味着广泛使用的方法提供了不准确的CPR测量结果并导致误解。结果表明，CPR测量的准确性由CPR导数的不对称性介导，而不是如先前认为的由临界电流介导。最后，我们针对通过最常用的参考结进行准确CPR测量提供了相关考虑因素。
