Over-the-Gap Conductance Oscillations in Superconducting Vanadium Nanocontacts Induced by Hydrogen Impurities

Md Saiful Islam, Hiroki Takata, Yuji Inagaki, Kenichi Hashizume, Tatsuya Kawae

研究成果: ジャーナルへの寄稿学術誌査読


We have investigated the current-voltage (I-V) characteristics of Josephson junctions made by a low-temperature superconductor of vanadium (V) with a small amount of hydrogen (H) and deuterium (D) impurities using a mechanically controllable break junction (MCBJ) technique. Below the superconducting transition temperature TC, the differential conductance dI/dV spectra show distinct peaks within the superconducting gap, known as the subgap structure, which result from multiple Andreev reflections in pure V nanocontacts. Additionally, the H and D impurities in V nanocontacts induce several new conductance peaks outside the gap, referred to as an over-the-gap structures (OGSs). We found that the OGS peaks exhibit strong temperature dependence until the temperature is close to TCand follow the gap function predicted by BCS theory. When the contact diameter is changed at low temperature using the MCBJ technique, the OGS anomalies change almost linearly with the inverse of the contact diameter. In addition, the gap anomalies are significantly shifted outward by changing the positions of the H atoms through application of a high bias voltage between the contacts. The above features suggest that the OGS peaks are caused by the superconducting quasiparticle interference induced by H or D impurities and/or inhomogeneous structures in the nanocontacts.

ジャーナルACS nano
出版ステータス出版済み - 9月 27 2022

!!!All Science Journal Classification (ASJC) codes

  • 材料科学(全般)
  • 工学(全般)
  • 物理学および天文学(全般)


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