Van der Waals Heterostructure Magnetic Josephson Junction

H. Idzuchi; F. Pientka; K. -F. Huang; K. Harada; Ö. Gül; Y. J. Shin; L. T. Nguyen; N. H. Jo; D. Shindo; R. J. Cava; P. C. Canfield; P. Kim

arXiv · 2012.14969

Van der Waals Heterostructure Magnetic Josephson Junction

H. Idzuchi·F. Pientka·K. -F. Huang·K. Harada·Ö. Gül·Y. J. Shin·L. T. Nguyen·N. H. Jo·D. Shindo·R. J. Cava·P. C. Canfield·P. Kim

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Abstract

When two superconductors are connected across a ferromagnet, the spin configuration of the transferred Cooper pairs can be modulated due to magnetic exchange interaction. The resulting supercurrent can reverse its sign across the Josephson junction (JJ) [1-4]. Here we demonstrate Josephson phase modulation in van der Waals heterostructures when Cooper pairs from superconducting NbSe$_2$ tunnel through atomically thin magnetic insulator (MI) Cr$_2$Ge$_2$Te$_6$. Employing a superconducting quantum interference device based on MI JJs, we probe a doubly degenerate non-trivial JJ phase ($\phi$) originating from the magnetic barrier. This $\phi$-phase JJ is formed by momentum conserving tunneling of Ising Cooper pairs [5] across magnetic domains in the Cr$_2$Ge$_2$Te$_6$ barrier. The doubly degenerate ground states in MI JJs provide a two-level quantum system that can be utilized as a new disipationless component for superconducting quantum devices, including phase batteries [6], memories [7,8], and quantum Ratchets [9,10].

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H. Idzuchi, F. Pientka, K. -F. Huang, K. Harada, Ö. Gül, Y. J. Shin, L. T. Nguyen, N. H. Jo, D. Shindo, R. J. Cava, P. C. Canfield, P. Kim. 2020-12-29. Van der Waals Heterostructure Magnetic Josephson Junction. https://arxiv.org/abs/2012.14969

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