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| VOLUME 123 (2026) | ISSUE 8 | PAGE 565 |
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Josephson diode and spin-valve effects on the surface of altermagnet CrSb
V. D. Esin+, D. Yu. Kazmin+, Yu. S. Barash+, A. V. Timonina+, N. N. Kolesnikov+, E. V. Deviatov*
+Institute of Solid State Physics of the Russian Academy of Sciences, 142432 Chernogolovka, Russia *V. L. Ginzburg Research Centre for High-Temperature Superconductivity and Quantum Materials, P. N. Lebedev Physical Institute of the Russian Academy of Sciences, 119991 Moscow, Russia
Abstract
We experimentally investigate charge transport in In-CrSb and In-CrSb-In proximity devices, which are formed as junctions between superconducting indium leads and thick single crystal flakes of altermagnet CrSb. For double In-CrSb-In junctions, dV/dI(B) curves are mirrored in respect to zero field for two magnetic field sweep directions, which is characteristic behavior of a Josephson spin valve. Also, we demonstrate Josephson diode effect by direct measurement of the critical current for two opposite directions in external magnetic field. We interpret these observations as a joint effect of the spin-polarized topological surface states and the altermagnetic spin splitting of the bulk bands in CrSb. For a single In-CrSb interface, the superconducting gap oscillates in magnetic field for both field orientations, which strongly resembles the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) behavior. FFLO is based on finite-momentum Cooper pairing, therefore, it is fully compatible with the requirements for the Josephson diode effect. |