Magnetic properties and spin dynamics have been studied for the structurally ordered double perovskite Sr2CoOsO6. Neutron diffraction, muon-spin relaxation, and ac-susceptibility measurements reveal two antiferromagnetic (AFM) phases on cooling from room temperature down to 2 K. In the first AFM phase, with transition temperature TN1=108 K, cobalt (3d7, S=3/2) and osmium (5d2, S=1) moments fluctuate dynamically, while their average effective moments undergo long-range order. In the second AFM phase below TN2=67 K, cobalt moments first become frozen and induce a noncollinear spin-canted AFM state, while dynamically fluctuating osmium moments are later frozen into a randomly canted state at T≈5 K. Ab initio calculations indicate that the effective exchange coupling between cobalt and osmium sites is rather weak, so that cobalt and osmium sublattices exhibit different ground states and spin dynamics, making Sr2CoOsO6 distinct from previously reported double-perovskite compounds.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1103/PhysRevLett.112.147202 | DOI Listing |
Small
January 2025
Materials Theory for Energy Scavenging (MATES) Lab, Harish-Chandra Research Institute, A CI of Homi Bhabha National Institute (HBNI), Chhatnag Road, Prayagraj, Uttar Pradesh, 211019, India.
Using first-principles GW (G is one-electron Green's function and W is the dynamical screening Coloumb potential) coupled Bethe-Salpeter equation (BSE) calculations with spin-orbit coupling, exceptionally strong excitonic effects are identified in several bismuth-based vacancy-ordered mixed halide double perovskites. These perovskites are thermodynamically stable with negative formation energy. For CsBiX (X = Cl,Br,I) double perovskites, both the bandgap and excitonic binding energy decrease as the size of the halogen atom increases.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai 200438, China.
It is always important and fascinating to explore new organic emitters that exploit unconventional pathways to unveil their emission with unique properties, such as thermally activated delayed fluorescence (TADF). In this study, we report that the rarely explored sulfur lone pair (n) is a promising alternative, where the correlated π* → n emission can be used to attain strong TADF and thus practical OLEDs. The designed strategy incorporates several key concepts (Figure 1a), in which the persulfide aromatic spirocycle enhances spin-orbit coupling, thereby increasing the intersystem crossing rate.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Department of Chemistry, University of California Davis, Davis, California 95616, United States.
[FeFe]-hydrogenases are enzymes that catalyze the redox interconversion of H and H using a six-iron active site, known as the H-cluster, which consists of a structurally unique [2Fe] subcluster linked to a [4Fe-4S] subcluster. A set of enzymes, HydG, HydE, and HydF, are responsible for the biosynthesis of the [2Fe] subcluster. Among them, it is well established that HydG cleaves tyrosine into CO and CN and forms a mononuclear [Fe(II)(Cys)(CO)(CN)] complex.
View Article and Find Full Text PDFNpj Spintron
January 2025
Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany.
The interplay of electronic charge, spin, and orbital currents, coherently driven by picosecond long oscillations of light fields in spin-orbit coupled systems, is the foundation of emerging terahertz lightwave spintronics and orbitronics. The essential rules for how terahertz fields interact with these systems in a nonlinear way are still not understood. In this work, we demonstrate a universally applicable electronic nonlinearity originating from spin-orbit interactions in conducting materials, wherein the interplay of light-induced spin and orbital textures manifests.
View Article and Find Full Text PDFNature
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 PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!