Ubiquitous missing first Shapiro step in Al-InSb nanosheet Josephson junctions

Fuente: arXiv
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Autori principali: Wu, Xingjun, Su, Haitian, Zeng, Chuanchang, Wang, Ji-Yin, Yan, Shili, Pan, Dong, Zhao, Jianhua, Zhang, Po, Xu, H. Q.
Natura: Preprint
Pubblicazione: 2024
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author Wu, Xingjun
Su, Haitian
Zeng, Chuanchang
Wang, Ji-Yin
Yan, Shili
Pan, Dong
Zhao, Jianhua
Zhang, Po
Xu, H. Q.
author_facet Wu, Xingjun
Su, Haitian
Zeng, Chuanchang
Wang, Ji-Yin
Yan, Shili
Pan, Dong
Zhao, Jianhua
Zhang, Po
Xu, H. Q.
contents The absence of odd-order Shapiro steps is a predicted signature of topological superconductors. Experimentally, the missing first-order Shapiro step has been reported in both putative topological superconducting systems and topologically trivial superconductor-semiconductor Josephson junctions. Here, we revisit this phenomenon in topologically trivial Al-InSb nanosheet Josephson junctions under microwave irradiation. The missing first Shapiro step coincides with a sharp voltage jump during superconducting switching, yet reappears when the jump is lowered and softened by increasing microwave power, temperature, or magnetic field. It also reappears at higher microwave frequencies, consistent with qualitative results from an RSJ model incorporating the sharp jump. These observations indicate that the absence of the first Shapiro step, associated with the sharp switching jump, simply results from their location within the measurement blind region. This work identifies a common but overlooked mechanism underlying the missing first Shapiro step, offering new insights into fractional Josephson effect experiments.
format Preprint
id arxiv_https___arxiv_org_abs_2403_07370
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Ubiquitous missing first Shapiro step in Al-InSb nanosheet Josephson junctions
Wu, Xingjun
Su, Haitian
Zeng, Chuanchang
Wang, Ji-Yin
Yan, Shili
Pan, Dong
Zhao, Jianhua
Zhang, Po
Xu, H. Q.
Superconductivity
The absence of odd-order Shapiro steps is a predicted signature of topological superconductors. Experimentally, the missing first-order Shapiro step has been reported in both putative topological superconducting systems and topologically trivial superconductor-semiconductor Josephson junctions. Here, we revisit this phenomenon in topologically trivial Al-InSb nanosheet Josephson junctions under microwave irradiation. The missing first Shapiro step coincides with a sharp voltage jump during superconducting switching, yet reappears when the jump is lowered and softened by increasing microwave power, temperature, or magnetic field. It also reappears at higher microwave frequencies, consistent with qualitative results from an RSJ model incorporating the sharp jump. These observations indicate that the absence of the first Shapiro step, associated with the sharp switching jump, simply results from their location within the measurement blind region. This work identifies a common but overlooked mechanism underlying the missing first Shapiro step, offering new insights into fractional Josephson effect experiments.
title Ubiquitous missing first Shapiro step in Al-InSb nanosheet Josephson junctions
topic Superconductivity
url https://arxiv.org/abs/2403.07370