We investigate Josephson coupling through a ferromagnetic thin film using superconductor-insulator-ferromagnet-superconductor planar junctions. Damped oscillations of the critical current are observed as a function of the ferromagnetic layer thickness. We show that they result from the exchange energy gained or lost by a quasiparticle Andreev-reflected at the ferromagnet-superconductor interface. The critical current cancels out at the transition from positive ("0") to negative ("pi") coupling, in agreement with theoretical calculations.
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http://dx.doi.org/10.1103/PhysRevLett.89.137007 | DOI Listing |
Nature
January 2025
Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea.
A particle current generated by pumping in the absence of gradients in potential energy, density or temperature is associated with non-trivial dynamics. A representative example is charge pumping that is associated with the quantum Hall effect and the quantum anomalous Hall effect. Spin pumping, the spin equivalent of charge pumping, refers to the emission of a spin current by magnetization dynamics.
View Article and Find Full Text PDFAdv Mater
January 2025
Department of Physics, University of Ulsan, Ulsan, 44619, South Korea.
Efficient magnetization control is a central issue in magnetism and spintronics. Particularly, there are increasing demands for manipulation of magnetic states in van der Waals (vdW) magnets with unconventional functionalities. However, the electrically induced phase transition between ferromagnetic-to-antiferromagnetic states without external magnetic field is yet to be demonstrated.
View Article and Find Full Text PDFSmall
January 2025
Department of Physics, Kyungpook National University, Daegu, 41566, South Korea.
The construction of multilevel magnetic states using materials with perpendicular magnetic anisotropy (PMA) offers a novel approach to enhancing the storage density and read/write efficiency of nonvolatile magnetic memory devices. In this study, optically readable multilevel magnetic domain states are achieved by inducing asymmetric interlayer interactions and decoupling the magnetic reversal behavior of individual ferromagnetic (FM) layers in exchange-biased FM multilayers with PMA. Hepta-level magnetic domain states are formed in [Co/Pt] FM multilayers grown on an antiferromagnetic FeO layer within a relatively low magnetic field range of ∼±400 Oe.
View Article and Find Full Text PDFMaterials (Basel)
January 2025
Department Physics and Astronomy, University of Notre Dame, Notre Dame, IN 46556, USA.
In this paper, we review our work on the manipulation of magnetization in ferromagnetic semiconductors (FMSs) using electric-current-induced spin-orbit torque (SOT). Our review focuses on FMS layers from the (Ga,Mn)As zinc-blende family grown by molecular beam epitaxy. We describe the processes used to obtain spin polarization of the current that is required to achieve SOT, and we briefly discuss methods of specimen preparation and of measuring the state of magnetization.
View Article and Find Full Text PDFSci Rep
January 2025
School of Physics Science and Engineering, Tongji University, Shanghai, 200092, People's Republic of China.
Two-dimensional van der Waals (2D vdW) materials have attracted widespread research interest due to their unique physical properties and potential application prospects. In this study, an atomistic-level dynamical simulation method is employed to investigate the chirality of antiferromagnetic resonance modes in CrI bilayer. Beyond the typical observations of a linear increase in high-frequency resonance mode and a linear decrease in low-frequency resonance mode, we have identified a distinct magnetization precession chirality in the CrI bilayer at low magnetic fields: Spins in different layers exhibit opposite precession chirality.
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