Phase biasing of a Josephson junction using Rashba-Edelstein effect
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arXiv
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| Format: | Preprint |
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2023
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| _version_ | 1866914630388940800 |
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| author | Senapati, Tapas Kumar, Ashwin Senapati, Kartik |
| author_facet | Senapati, Tapas Kumar, Ashwin Senapati, Kartik |
| contents | Manifestation of orbital coupling of spin degree of freedom in condensed matter systems has opened up a new dimension for the field of spintronics. The most appealing aspect of the spin-orbit coupling is the apparent Magnus force sensed by a spin system which locks the Fermi momentum with electron spin in a fascinating manner. In the current carrying state, the resulting macroscopic spin polarization becomes directly accessible in the form of spin current or spin density. At a Rashba interface, for example, a charge current shifts the spin-locked Fermi surface, leading to a non-equilibrium spin density at the interface, commonly known as the Rashba-Edelstein effect. Since the Rashba-Edelstein effect is an intrinsically interface property, direct detection of the spin moment is harder to set-up. Here we demonstrate that a simple planar Josephson Junction geometry, realized by placing two closely spaced superconducting electrodes on such a Rashba interface, allows a direct estimation of strength of the non-equilibrium spin moment. Measurements of Fraunhofer patterns of Nb-(Pt/Cu)-Nb planar Josephson junctions in a perpendicular magnetic field showed a shift of the center of the Fraunhofer pattern to a non-zero field value. By performing extensive control measurements, we argue that the screening currents in the junction effectively lock the external field with the spin moment of the Rashba-Edelstein effect induced spin-density, leading to the observed shift in the Fraunhofer patterns. This simple experiment offers a fresh perspective on direct detection of spin polarization induced by various spin-orbit effects. Very interestingly, this device platform also offers the possibility of retaining a controllable phase at zero field in the junction without using any magnetic material, and thereby useful as phase batteries for superconducting quantum circuits. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2304_11457 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Phase biasing of a Josephson junction using Rashba-Edelstein effect Senapati, Tapas Kumar, Ashwin Senapati, Kartik Mesoscale and Nanoscale Physics Superconductivity Manifestation of orbital coupling of spin degree of freedom in condensed matter systems has opened up a new dimension for the field of spintronics. The most appealing aspect of the spin-orbit coupling is the apparent Magnus force sensed by a spin system which locks the Fermi momentum with electron spin in a fascinating manner. In the current carrying state, the resulting macroscopic spin polarization becomes directly accessible in the form of spin current or spin density. At a Rashba interface, for example, a charge current shifts the spin-locked Fermi surface, leading to a non-equilibrium spin density at the interface, commonly known as the Rashba-Edelstein effect. Since the Rashba-Edelstein effect is an intrinsically interface property, direct detection of the spin moment is harder to set-up. Here we demonstrate that a simple planar Josephson Junction geometry, realized by placing two closely spaced superconducting electrodes on such a Rashba interface, allows a direct estimation of strength of the non-equilibrium spin moment. Measurements of Fraunhofer patterns of Nb-(Pt/Cu)-Nb planar Josephson junctions in a perpendicular magnetic field showed a shift of the center of the Fraunhofer pattern to a non-zero field value. By performing extensive control measurements, we argue that the screening currents in the junction effectively lock the external field with the spin moment of the Rashba-Edelstein effect induced spin-density, leading to the observed shift in the Fraunhofer patterns. This simple experiment offers a fresh perspective on direct detection of spin polarization induced by various spin-orbit effects. Very interestingly, this device platform also offers the possibility of retaining a controllable phase at zero field in the junction without using any magnetic material, and thereby useful as phase batteries for superconducting quantum circuits. |
| title | Phase biasing of a Josephson junction using Rashba-Edelstein effect |
| topic | Mesoscale and Nanoscale Physics Superconductivity |
| url | https://arxiv.org/abs/2304.11457 |