We measure the mode-resolved direction of the precessional motion of the magnetic order, i.e., magnon polarization, via the chiral term of inelastic polarized neutron scattering spectra. The magnon polarization is a unique and unambiguous signature of magnets and is important in spintronics, affecting thermodynamic properties such as the magnitude and sign of the spin Seebeck effect. However, it has never been directly measured in any material until this work. The observation of both signs of magnon polarization in Y_{3}Fe_{5}O_{12} also gives direct proof of its ferrimagnetic nature. The experiments agree very well with atomistic simulations of the scattering cross section.
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http://dx.doi.org/10.1103/PhysRevLett.125.027201 | DOI Listing |
Adv Mater
January 2025
Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia.
The chirality of magnons, exhibiting left- and right-handed polarizations analogous to the counterparts of spin-up and spin-down, has emerged as a promising paradigm for information processing. However, the potential of this paradigm is constrained by the controllable excitation and transmission of chiral magnons. Here, the magnon transmission is explored in the GdFeO/NiO/Pt structures.
View Article and Find Full Text PDFNano Lett
December 2024
International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, P.R. China.
Half-metals are a class of quantum materials with 100% spin polarization at the Fermi level and have attracted a lot of attention for future spintronic device applications. CrO is one of the most promising half-metal candidates for which the electrical and magnetic properties have been intensively studied in the last several decades. Here, we report the observation of a giant anisotropy (∼1600%) of effective Gilbert damping in the single-crystalline half-metallic (100)-CrO thin films, which is significantly larger than the values observed on conventional ferromagnetic Fe and CoFe thin films.
View Article and Find Full Text PDFNpj Spintron
December 2024
James Watt School of Engineering, Electronics & Nanoscale Engineering Division, University of Glasgow, Glasgow, G12 8QQ UK.
Recently the field of cavity magnonics, a field focused on controlling the interaction between magnons and photons confined within microwave resonators, has drawn significant attention as it offers a platform for enabling advancements in quantum- and spin-based technologies. Here, we introduce excitation vector fields, whose polarisation and profile can be easily tuned in a two-port cavity setup, thus acting as an effective experimental dial to explore the coupled dynamics of cavity magnon-polaritons. Moreover, we develop theoretical models that accurately predict and reproduce the experimental results for any polarisation state and field profile within the cavity resonator.
View Article and Find Full Text PDFSci Adv
November 2024
Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
We uncover a superconducting state with partial spin polarization induced by a magnetic field. This state, which we call "magnonic superconductor," lacks a conventional pairing order parameter but is characterized instead by a composite order parameter that represents the binding of electron pairs and magnons. We rigorously demonstrate the existence of magnonic superconductivity with high transition temperature in one-dimensional and two-dimensional Hubbard models with repulsive interaction.
View Article and Find Full Text PDFNat Commun
November 2024
Institute for Chemical Research, Kyoto University, Uji, Kyoto, 611-0011, Japan.
Antiferromagnetic magnons possess a distinctive feature absent in their ferromagnetic counterparts: the presence of two distinct handedness modes, the right-handed (RH) and left-handed (LH) precession modes. The magnon handedness determines the sign of spin polarization carried by the propagating magnon, which is indispensable for harnessing the diverse functionalities in magnonic devices, such as data encoding, magnon polarization-based logic systems, and quantum applications involving magnons. However, the control of coherently propagating magnon handedness in antiferromagnets has remained elusive.
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