In spin electronics, the spin degree of freedom is used to transmit and store information. To this end the ability to create pure spin currents--that is, without net charge transfer--is essential. When the magnetization vector in a ferromagnet-normal metal junction is excited, the spin pumping effect leads to the injection of pure spin currents into the normal metal. The polarization of this spin current is time-dependent and contains a very small d.c. component. Here we show that the large a.c. component of the spin currents can be detected efficiently using the inverse spin Hall effect. The observed a.c.-inverse spin Hall voltages are one order of magnitude larger than the conventional d.c.-inverse spin Hall voltages measured on the same device. Our results demonstrate that ferromagnet-normal metal junctions are efficient sources of pure spin currents in the gigahertz frequency range.
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http://dx.doi.org/10.1038/ncomms4768 | DOI Listing |
ACS Appl Mater Interfaces
January 2025
School of Physical Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Kolkata 700032, India.
Materials exhibiting topological transport properties, such as a large topological Hall resistivity, are crucial for next-generation spintronic devices. Here, we report large topological Hall resistivities in epitaxial supermalloy (NiFeMo) thin films with [100] and [111] orientations grown on single-crystal MgO (100) and AlO (0001) substrates, respectively. While X-ray reciprocal maps confirmed the epitaxial growth of the films, X-ray stress analyses revealed large residual strains in the films, inducing tetragonal distortions of the cubic NiFeMo unit cells.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2025
College of Sciences, Northeastern University, Shenyang, 110819, China.
In this work, using first-principles calculations, we predict a promising class of two-dimensional ferromagnetic semiconductors, namely Janus PrXY (X ≠ Y = Cl, Br, I) monolayers. Through first-principles calculations, we found that PrXY monolayers have excellent dynamic and thermal stability, and their band structures, influenced by magnetic exchange and spin-orbital coupling, exhibit significant valley polarization. Between and - valleys, the Berry curvature values are opposite to each other, resulting in the anomalous valley Hall effect.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.
Chiral magnetic textures give rise to unconventional magnetotransport phenomena such as the topological Hall effect and nonreciprocal electronic transport. While the correspondence between topology or symmetry of chiral magnetic structures and such transport phenomena has been well established, a microscopic understanding based on the spin-dependent band structure in momentum space remains elusive. Here, we demonstrate how a chiral magnetic superstructure introduces an asymmetry in the electronic band structure and triggers a nonreciprocal electronic transport in a centrosymmetric helimagnet α-EuP.
View Article and Find Full Text PDFAdv Mater
January 2025
Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin, 53706, USA.
Unconventional spin-orbit torques arising from electric-field-generated spin currents in anisotropic materials have promising potential for spintronic applications, including for perpendicular magnetic switching in high-density memory applications. Here, all the independent elements of the spin torque conductivity tensor allowed by bulk crystal symmetries for the tetragonal conductor IrO are determined via measurements of conventional (in-plane) anti-damping torques for IrO thin films in the high-symmetry (001) and (100) orientations. It is then tested whether rotational transformations of this same tensor can predict both the conventional and unconventional anti-damping torques for IrO thin films in the lower-symmetry (101), (110), and (111) orientations, finding good agreement.
View Article and Find Full Text PDFAdv Mater
January 2025
Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, CB3 0FS, UK.
Thick metamorphic buffers are considered indispensable for III-V semiconductor heteroepitaxy on large lattice and thermal-expansion mismatched silicon substrates. However, III-nitride buffers in conventional GaN-on-Si high electron mobility transistors (HEMT) impose a substantial thermal resistance, deteriorating device efficiency and lifetime by throttling heat extraction. To circumvent this, a systematic methodology for the direct growth of GaN after the AlN nucleation layer on six-inch silicon substrates is demonstrated using metal-organic vapor phase epitaxy (MOVPE).
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