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1.
Cell ; 175(2): 472-487.e20, 2018 10 04.
Artigo em Inglês | MEDLINE | ID: mdl-30146164

RESUMO

The dorsal raphe (DR) constitutes a major serotonergic input to the forebrain and modulates diverse functions and brain states, including mood, anxiety, and sensory and motor functions. Most functional studies to date have treated DR serotonin neurons as a single population. Using viral-genetic methods, we found that subcortical- and cortical-projecting serotonin neurons have distinct cell-body distributions within the DR and differentially co-express a vesicular glutamate transporter. Further, amygdala- and frontal-cortex-projecting DR serotonin neurons have largely complementary whole-brain collateralization patterns, receive biased inputs from presynaptic partners, and exhibit opposite responses to aversive stimuli. Gain- and loss-of-function experiments suggest that amygdala-projecting DR serotonin neurons promote anxiety-like behavior, whereas frontal-cortex-projecting neurons promote active coping in the face of challenge. These results provide compelling evidence that the DR serotonin system contains parallel sub-systems that differ in input and output connectivity, physiological response properties, and behavioral functions.


Assuntos
Núcleo Dorsal da Rafe/anatomia & histologia , Núcleo Dorsal da Rafe/fisiologia , Serotonina/fisiologia , Adaptação Psicológica/fisiologia , Tonsila do Cerebelo/fisiologia , Animais , Ansiedade/fisiopatologia , Encéfalo/fisiologia , Núcleo Dorsal da Rafe/metabolismo , Feminino , Lobo Frontal/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/fisiologia , Serotonina/metabolismo
2.
Mol Cell ; 75(6): 1161-1177.e11, 2019 09 19.
Artigo em Inglês | MEDLINE | ID: mdl-31421980

RESUMO

Genes are transcribed in a discontinuous pattern referred to as RNA bursting, but the mechanisms regulating this process are unclear. Although many physiological signals, including glucocorticoid hormones, are pulsatile, the effects of transient stimulation on bursting are unknown. Here we characterize RNA synthesis from single-copy glucocorticoid receptor (GR)-regulated transcription sites (TSs) under pulsed (ultradian) and constant hormone stimulation. In contrast to constant stimulation, pulsed stimulation induces restricted bursting centered around the hormonal pulse. Moreover, we demonstrate that transcription factor (TF) nuclear mobility determines burst duration, whereas its bound fraction determines burst frequency. Using 3D tracking of TSs, we directly correlate TF binding and RNA synthesis at a specific promoter. Finally, we uncover a striking co-bursting pattern between TSs located at proximal and distal positions in the nucleus. Together, our data reveal a dynamic interplay between TF mobility and RNA bursting that is responsive to stimuli strength, type, modality, and duration.


Assuntos
Glucocorticoides/farmacologia , Regiões Promotoras Genéticas , RNA/biossíntese , Receptores de Glucocorticoides/metabolismo , Sítio de Iniciação de Transcrição , Transcrição Gênica/efeitos dos fármacos , Animais , Camundongos , RNA/genética
3.
Proc Natl Acad Sci U S A ; 121(16): e2319119121, 2024 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-38588435

RESUMO

The advancement of atomically precise dinuclear heterogeneous catalysts holds great potential in achieving efficient catalytic ozonation performance and contributes to the understanding of synergy mechanisms during reaction conditions. Herein, we demonstrate a "ship-in-a-bottle and pyrolysis" strategy that utilizes Fe2(CO)9 dinuclear-cluster to precisely construct Fe2 site, consisting of two Fe1-N3 units connected by Fe-Fe bonds and firmly bonded to N-doped carbon. Systematic characterizations and theoretical modeling reveal that the Fe-Fe coordination motif markedly reduced the devotion of the antibonding state in the Fe-O bond because of the strong orbital coupling interaction of dual Fe d-d orbitals. This facilitates O-O covalent bond cleavage of O3 and enhances binding strength with reaction intermediates (atomic oxygen species; *O and *OO), thus boosting catalytic ozonation performance. As a result, Fe dinuclear site catalyst exhibits 100% ozonation efficiency for CH3SH elimination, outperforming commercial MnO2 catalysts by 1,200-fold. This research provides insights into the atomic-level structure-activity relationship of ozonation catalysts and extends the use of dinuclear catalysts in catalytic ozonation and beyond.

4.
Proc Natl Acad Sci U S A ; 120(48): e2305541120, 2023 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-37983495

RESUMO

The interplay between chirality and topology nurtures many exotic electronic properties. For instance, topological chiral semimetals display multifold chiral fermions that manifest nontrivial topological charge and spin texture. They are an ideal playground for exploring chirality-driven exotic physical phenomena. In this work, we reveal a monopole-like orbital-momentum locking texture on the three-dimensional Fermi surfaces of topological chiral semimetals with B20 structures (e.g., RhSi and PdGa). This orbital texture enables a large orbital Hall effect (OHE) and a giant orbital magnetoelectric (OME) effect in the presence of current flow. Different enantiomers exhibit the same OHE which can be converted to the spin Hall effect by spin-orbit coupling in materials. In contrast, the OME effect is chirality-dependent and much larger than its spin counterpart. Our work reveals the crucial role of orbital texture for understanding OHE and OME effects in topological chiral semimetals and paves the path for applications in orbitronics, spintronics, and enantiomer recognition.

5.
Proc Natl Acad Sci U S A ; 120(25): e2301439120, 2023 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-37307482

RESUMO

Catalysts with a refined electronic structure are highly desirable for promoting the oxygen evolution reaction (OER) kinetics and reduce the charge overpotentials for lithium-oxygen (Li-O2) batteries. However, bridging the orbital interactions inside the catalyst with external orbital coupling between catalysts and intermediates for reinforcing OER catalytic activities remains a grand challenge. Herein, we report a cascaded orbital-oriented hybridization, namely alloying hybridization in intermetallic Pd3Pb followed by intermolecular orbital hybridization between low-energy Pd atom and reaction intermediates, for greatly enhancing the OER electrocatalytic activity in Li-O2 battery. The oriented orbital hybridization in two axes between Pb and Pd first lowers the d band energy level of Pd atoms in the intermetallic Pd3Pb; during the charging process, the low-lying 4dxz/yz and 4dz2 orbital of the Pd further hybridizes with 2π* and 5σ orbitals of lithium superoxide (LiO2) (key reaction intermediate), eventually leading to lower energy levels of antibonding and, thus, weakened orbital interaction toward LiO2. As a consequence, the cascaded orbital-oriented hybridization in intermetallic Pd3Pb considerably decreases the activation energy and accelerates the OER kinetics. The Pd3Pb-based Li-O2 batteries exhibit a low OER overpotential of 0.45 V and superior cycle stability of 175 cycles at a fixed capacity of 1,000 mAh g-1, which is among the best in the reported catalysts. The present work opens up a way for designing sophisticated Li-O2 batteries at the orbital level.

6.
Proc Natl Acad Sci U S A ; 120(23): e2217398120, 2023 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-37252955

RESUMO

We investigate the underlying distribution of orbital eccentricities for planets around early-to-mid M dwarf host stars. We employ a sample of 163 planets around early- to mid-M dwarfs across 101 systems detected by NASA's Kepler Mission. We constrain the orbital eccentricity for each planet by leveraging the Kepler lightcurve together with a stellar density prior, constructed using metallicity from spectroscopy, Ks magnitude from 2MASS, and stellar parallax from Gaia. Within a Bayesian hierarchical framework, we extract the underlying eccentricity distribution, assuming alternately Rayleigh, half-Gaussian, and Beta functions for both single- and multi-transit systems. We described the eccentricity distribution for apparently single-transiting planetary systems with a Rayleigh distribution with [Formula: see text], and for multitransit systems with [Formula: see text]. The data suggest the possibility of distinct dynamically warmer and cooler subpopulations within the single-transit distribution: The single-transit data prefer a mixture model composed of two distinct Rayleigh distributions with [Formula: see text] and [Formula: see text] over a single Rayleigh distribution, with 7:1 odds. We contextualize our findings within a planet formation framework, by comparing them to analogous results in the literature for planets orbiting FGK stars. By combining our derived eccentricity distribution with other M dwarf demographic constraints, we estimate the underlying eccentricity distribution for the population of early- to mid-M dwarf planets in the local neighborhood.

7.
Proc Natl Acad Sci U S A ; 120(13): e2217208120, 2023 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-36940337

RESUMO

Intercalation-type layered oxides have been widely explored as cathode materials for aqueous zinc-ion batteries (ZIBs). Although high-rate capability has been achieved based on the pillar effect of various intercalants for widening interlayer space, an in-depth understanding of atomic orbital variations induced by intercalants is still unknown. Herein, we design an NH4+-intercalated vanadium oxide (NH4+-V2O5) for high-rate ZIBs, together with deeply investigating the role of the intercalant in terms of atomic orbital. Besides extended layer spacing, our X-ray spectroscopies reveal that the insertion of NH4+ could promote electron transition to 3dxy state of V t2g orbital in V2O5, which significantly accelerates the electron transfer and Zn-ion migration, further verified by DFT calculations. As results, the NH4+-V2O5 electrode delivers a high capacity of 430.0 mA h g-1 at 0.1 A g-1, especially excellent rate capability (101.0 mA h g-1 at 200 C), enabling fast charging within 18 s. Moreover, the reversible V t2g orbital and lattice space variation during cycling are found via ex-situ soft X-ray absorption spectrum and in-situ synchrotron radiation X-ray diffraction, respectively. This work provides an insight at orbital level in advanced cathode materials.

8.
Proc Natl Acad Sci U S A ; 120(17): e2211495120, 2023 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-37068228

RESUMO

Whether there are links between geomagnetic field and Earth's orbital parameters remains unclear. Synchronous reconstructions of parallel long-term quantitative geomagnetic field and climate change records are rare. Here, we present 10Be-derived changes of both geomagnetic field and Asian monsoon (AM) rainfall over the last 870 kyr from the Xifeng loess-paleosol sequence on the central Chinese Loess Plateau. The 10BeGM flux (a proxy for geomagnetic field-induced 10Be production rate) reveals 13 consecutive geomagnetic excursions in the Brunhes chron, which are synchronized with the global records, providing key time markers for Chinese loess-paleosol sequences. The 10Be-derived rainfall exhibits distinct ~100 kyr glacial-interglacial cycles, and superimposed precessional (~23 kyr) cycles that match with those in Chinese speleothem δ18O record. We find that changes in the geomagnetic field and AM rainfall share a common ~100 kyr cyclicity, implying a likely eccentricity modulation of both the geomagnetic field and climate.

9.
Proc Natl Acad Sci U S A ; 120(21): e2219661120, 2023 May 23.
Artigo em Inglês | MEDLINE | ID: mdl-37186826

RESUMO

The oxygen evolution reaction (OER) underpins many aspects of energy storage and conversion in modern industry and technology, but which still be suffering from the dilemma of sluggish reaction kinetics and poor electrochemical performance. Different from the viewpoint of nanostructuring, this work focuses on an intriguing dynamic orbital hybridization approach to renormalize the disordering spin configuration in porous noble-metal-free metal-organic frameworks (MOFs) to accelerate the spin-dependent reaction kinetics in OER. Herein, we propose an extraordinary super-exchange interaction to reconfigure the domain direction of spin nets at porous MOFs through temporarily bonding with dynamic magnetic ions in electrolytes under alternating electromagnetic field stimulation, in which the spin renormalization from disordering low-spin state to high-spin state facilitates rapid water dissociation and optimal carrier migration, leading to a spin-dependent reaction pathway. Therefore, the spin-renormalized MOFs demonstrate a mass activity of 2,095.1 A gmetal-1 at an overpotential of 0.33 V, which is about 5.9 time of pristine ones. Our findings provide a insight into reconfiguring spin-related catalysts with ordering domain directions to accelerate the oxygen reaction kinetics.

10.
J Biol Chem ; 300(2): 105599, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38159853

RESUMO

It is known that the recommended dietary allowance of selenium (Se) is dangerously close to its tolerable upper intake level. Se is detoxified and excreted in urine as trimethylselenonium ion (TMSe) when the amount ingested exceeds the nutritional level. Recently, we demonstrated that the production of TMSe requires two methyltransferases: thiopurine S-methyltransferase (TPMT) and indolethylamine N-methyltransferase (INMT). In this study, we investigated the substrate recognition mechanisms of INMT and TPMT in the Se-methylation reaction. Examination of the Se-methyltransferase activities of two paralogs of INMT, namely, nicotinamide N-methyltransferase and phenylethanolamine N-methyltransferase, revealed that only INMT exhibited Se-methyltransferase activity. Consistently, molecular dynamics simulations demonstrated that dimethylselenide was preferentially associated with the active center of INMT. Using the fragment molecular orbital method, we identified hydrophobic residues involved in the binding of dimethylselenide to the active center of INMT. The INMT-L164R mutation resulted in a deficiency in Se- and N-methyltransferase activities. Similarly, TPMT-R152, which occupies the same position as INMT-L164, played a crucial role in the Se-methyltransferase activity of TPMT. Our findings suggest that TPMT recognizes negatively charged substrates, whereas INMT recognizes electrically neutral substrates in the hydrophobic active center embedded within the protein. These observations explain the sequential requirement of the two methyltransferases in producing TMSe.


Assuntos
Metiltransferases , Selênio , Metiltransferases/genética , Metiltransferases/metabolismo , Selênio/metabolismo , Metilação , Ativação Enzimática , Interações Hidrofóbicas e Hidrofílicas , Ligação Proteica , Humanos
11.
J Cell Sci ; 136(6)2023 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-36846872

RESUMO

Multidirectional or disturbed flow promotes endothelial dysfunction and is associated with early atherogenesis. Here we investigated the role of Wnt signalling in flow-mediated endothelial dysfunction. The expression of Frizzled-4 was higher in cultured human aortic endothelial cells (ECs) exposed to disturbed flow compared to that seen for undisturbed flow, obtained using an orbital shaker. Increased expression was also detected in regions of the porcine aortic arch exposed to disturbed flow. The increased Frizzled-4 expression in cultured ECs was abrogated following knockdown of R-spondin-3. Disturbed flow also increased the nuclear localisation and activation of ß-catenin, an effect that was dependent on Frizzled-4 and R-spondin-3. Inhibition of ß-catenin using the small-molecule inhibitor iCRT5 or knockdown of Frizzled-4 or R-spondin-3 resulted in reduced expression of pro-inflammatory genes in ECs exposed to disturbed flow, as did inhibition of WNT5A signalling. Inhibition of the canonical Wnt pathway had no effect. Inhibition of ß-catenin also reduced endothelial paracellular permeability; this was associated with altered junctional and focal adhesion organisation and cytoskeletal remodelling. These data suggest the presence of an atypical Frizzled-4-ß-catenin pathway that promotes endothelial dysfunction in response to disturbed flow.


Assuntos
Células Endoteliais , beta Catenina , Animais , Humanos , beta Catenina/genética , beta Catenina/metabolismo , Células Endoteliais/metabolismo , Inflamação/metabolismo , Permeabilidade , Suínos , Via de Sinalização Wnt , Receptores Frizzled/metabolismo
12.
Cereb Cortex ; 34(1)2024 01 14.
Artigo em Inglês | MEDLINE | ID: mdl-37943770

RESUMO

Empathic function, which is primarily manifested by facial imitation, is believed to play a pivotal role in interpersonal emotion regulation for mood reinstatement. To explore this association and its neural substrates, we performed a questionnaire survey (study l) to identify the relationship between empathy and interpersonal emotion regulation; and a task-mode fMRI study (study 2) to explore how facial imitation, as a fundamental component of empathic processes, promotes the interpersonal emotion regulation effect. Study 1 showed that affective empathy was positively correlated with interpersonal emotion regulation. Study 2 showed smaller negative emotions in facial imitation interpersonal emotion regulation (subjects imitated experimenter's smile while followed the interpersonal emotion regulation guidance) than in normal interpersonal emotion regulation (subjects followed the interpersonal emotion regulation guidance) and Watch conditions. Mirror neural system (e.g. inferior frontal gyrus and inferior parietal lobe) and empathy network exhibited greater activations in facial imitation interpersonal emotion regulation compared with normal interpersonal emotion regulation condition. Moreover, facial imitation interpersonal emotion regulation compared with normal interpersonal emotion regulation exhibited increased functional coupling from mirror neural system to empathic and affective networks during interpersonal emotion regulation. Furthermore, the connectivity of the right orbital inferior frontal gyrus-rolandic operculum lobe mediated the association between the accuracy of facial imitation and the interpersonal emotion regulation effect. These results show that the interpersonal emotion regulation effect can be enhanced by the target's facial imitation through increased functional coupling from mirror neural system to empathic and affective neural networks.


Assuntos
Regulação Emocional , Humanos , Mapeamento Encefálico/métodos , Comportamento Imitativo/fisiologia , Imageamento por Ressonância Magnética/métodos , Empatia , Neuroimagem Funcional , Emoções/fisiologia , Expressão Facial
13.
Proc Natl Acad Sci U S A ; 119(46): e2203818119, 2022 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-36343239

RESUMO

Orbital cyclicity is a fundamental pacemaker of Earth's climate system. The Newark-Hartford Basin (NHB) lake sediment record of eastern North America contains compelling geologic expressions of this cyclicity, reflecting variations of climatic conditions in tropical Pangea during the Late Triassic and earliest Jurassic (~233 to 199 Ma). Climate modeling enables a deeper mechanistic understanding of Earth system modulation during this unique greenhouse and supercontinent period. We link major features of the NHB record to the combined climatic effects of orbital forcing, paleogeographic changes, and atmospheric pCO[Formula: see text] variations. An ensemble of transient, orbitally driven climate simulations is assessed for nine time slices, three atmospheric pCO[Formula: see text] values, and two paleogeographic reconstructions. Climatic transitions from tropical humid to more seasonal and ultimately semiarid are associated with tectonic drift of the NHB from [Formula: see text] to [Formula: see text]. The modeled orbital modulation of the precipitation-evaporation balance is most pronounced during the 220 to 200 Ma interval, whereas it is limited by weak seasonality and increasing aridity before and after this interval. Lower pCO[Formula: see text] at around 205 Ma contributes to drier climates and could have led to the observed damping of sediment cyclicity. Eccentricity-modulated precession dominates the orbitally driven climate response in the NHB region. High obliquity further amplifies summer precipitation through the seasonal shifts in the tropical rainfall belt. Regions with other proxy records are also assessed, providing guidance toward an integrated picture of global astronomical climate forcing in the Late Triassic and ultimately of other periods in Earth history.


Assuntos
Planeta Terra , Lagos , Estações do Ano
14.
Nano Lett ; 2024 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-39374927

RESUMO

The study of open-shell nanographenes has relied on a paradigm where spins are the only low-energy degrees of freedom. Here we show that some nanographenes can host low-energy excitations that include strongly coupled spin and orbital degrees of freedom. The key ingredient is the existence of orbital degeneracy, as a consequence of leaving the benzenoid/half-filling scenario. We analyze the case of nitrogen-doped triangulenes, using both density-functional theory and Hubbard model multiconfigurational and random-phase approximation calculations. We find a rich interplay between orbital and spin degrees of freedom that confirms the need to go beyond the spin-only paradigm, opening a new avenue in this field of research.

15.
Nano Lett ; 24(43): 13465-13472, 2024 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-39433297

RESUMO

Recent experiments by S. Krishnia et al. [Nano Lett. 2023, 23, 6785] reported an unprecedentedly large enhancement of torques upon inserting thin Al layer in Co/Pt heterostructure that suggested the presence of a Rashba-like interaction at the metallic Co/Al interface. Based on first-principles calculations, we reveal the emergence of a large helical orbital texture in reciprocal space at the interfacial Co layer, whose origin is attributed to the orbital Rashba effect due to the formation of the surface states at the Co/Al interface and where spin-orbit coupling is found to produce smaller contributions with a higher-order winding of the orbital moments. Our results unveil that the orbital texture gives rise to a nonequilibrium orbital accumulation producing large current-induced torques, thus providing an essential theoretical background for the experimental data and advancing the use of orbital transport phenomena in all-metallic magnetic systems with light elements.

16.
Nano Lett ; 2024 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-39454116

RESUMO

Orbital torque (OT) in magnetic heterostructures has been actively discussed in terms of its actual existence and usefulness in comparison to the spin-orbit torque (SOT) that shows promise for next-generation magnetoresistive random access memories. The objectives of this study are 2-fold: (i) making an apples-to-apples comparison in two representative stacks where OT and SOT are expected to dominate and (ii) examining the potential emergence of OT in archetypal SOT stacks. Cr/CoFeB/MgO and W/CoFeB/MgO are chosen as the OT- and SOT-dominant systems, respectively. Systematic variations in each layer's thicknesses reveal that (i) Cr/CoFeB/MgO exhibits substantial torque comparable to or even exceeding that of the W/CoFeB/MgO stack when Cr and CoFeB layers are especially thick and (ii) the torque in W/CoFeB/MgO changes sign with increasing W and CoFeB thicknesses, suggesting a crossover of the dominant mechanism from SOT to OT. The findings clarify the opportunities and challenges of devices leveraging SOT and OT.

17.
Nano Lett ; 2024 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-39484830

RESUMO

Deeply understanding how local microstrain environment around diatomic sites influences their electronic state and adsorption is crucial for improving electrochemical CO2 reduction (eCO2R) reaction; however, precise engineering of the atomic microstrain environment is challenging. Herein, we fabricate Ag-CdTMT electrocatalysts with AgN2S2-CdN2S2 diatomic sites by anchoring Ag to the nodes of CdTMT (TMT = 2,4,6-trimercaptotriazine anion) coordination polymers. The Ag-CdTMT catalysts achieve approximately 100% Faradaic efficiency for CO reduction with an industrial level current density (∼200 mA cm-2 in H-cell). The embedded Ag atoms induce the formation of Ag-Cd diatomic sites with local microstrain, stretching Cd-N/S bonds, and reinforcing electron localization at Cd sites. The microstrain engineering and adjacent Ag atoms synergistically reduced Cd 4d-C 2p antibonding orbital occupancy for intensifying *COOH adsorption as the rate-determining step. This study provides novel insights into customizing the electronic structure of diatomic sites through strain engineering.

18.
Nano Lett ; 24(11): 3541-3547, 2024 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-38451854

RESUMO

Two-dimensional (2D) multiferroic materials have widespread application prospects in facilitating the integration and miniaturization of nanodevices. However, the magnetic, ferroelectric, and ferrovalley properties in one 2D material are rarely coupled. Here, we propose a mechanism for manipulating magnetism, ferroelectric, and valley polarization by interlayer sliding in a 2D bilayer material. Monolayer GdI2 is a ferromagnetic semiconductor with a valley polarization of up to 155.5 meV. More interestingly, the magnetism and valley polarization of bilayer GdI2 can be strongly coupled by sliding ferroelectricity, making these tunable and reversible. In addition, we uncover the microscopic mechanism of the magnetic phase transition by a spin Hamiltonian and electron hopping between layers. Our findings offer a new direction for investigating 2D multiferroic devices with implications for next-generation electronic, valleytronic, and spintronic devices.

19.
Nano Lett ; 24(20): 5968-5974, 2024 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-38682941

RESUMO

Recently, topological responses of magnons have emerged as a central theme in magnetism and spintronics. However, resulting Hall responses are typically weak and infrequent, since, according to present understanding, they arise from effective spin-orbit couplings, which are weaker compared to the exchange energy. Here, by investigating transport properties of magnon orbital moments, we predict that the magnon orbital Nernst effect is an intrinsic characteristic of the honeycomb antiferromagnet and therefore, it manifests even in the absence of spin-orbit coupling. For the electric detection, we propose an experimental scheme based on the magnetoelectric effect. Our results break the conventional wisdom that the Hall transport of magnons requires spin-orbit coupling by predicting the magnon orbital Nernst effect in a system without it, which leads us to envision that our work initiates the intensive search for various magnon Hall effects in generic magnetic systems with no reliance on spin-orbit coupling.

20.
Nano Lett ; 24(33): 10251-10257, 2024 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-39133560

RESUMO

Charge-spin interconversion processes underpin the generation of spin-orbit torques in magnetic/nonmagnetic bilayers. However, efficient sources of spin currents such as 5d metals are also efficient spin sinks, resulting in a large increase of magnetic damping. Here we show that a partially oxidized 3d metal can generate a strong orbital torque without a significant increase in damping. Measurements of the torque efficiency ξ and Gilbert damping α in CoFe/CuOx and CoFe/Pt indicate that ξ is comparable in the two systems. The increase in damping relative to a single CoFe layer is Δα < 0.002 in CoFe/CuOx and Δα ≈ 0.005-0.02 in CoFe/Pt, depending on CoFe thickness. We ascribe the nonreciprocal relationship between Δα and ξ in CoFe/CuOx to the small orbital-spin current ratio generated by magnetic resonance in CoFe and the lack of an efficient spin sink in CuOx. Our findings provide new perspectives on the efficient excitation of magnetization dynamics via the orbital torque.

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