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The well-known Hall effect describes the transverse deflection of charged particles (electrons/holes) as a result of the Lorentz force. Similarly, it is intriguing to examine if quasi-particles without an electric charge, but with a topological charge, show related transverse motion. Magnetic skyrmions with a well-defined spin texture with a unit topological charge serve as good candidates to test this hypothesis. In spite of the recent progress made on investigating magnetic skyrmions, direct observation of the skyrmion Hall effect has remained elusive. Here, by using a current-induced spin Hall spin torque, we experimentally demonstrate the skyrmion Hall effect, and the resultant skyrmion accumulation, by driving skyrmions from the creep-motion regime (where their dynamics are influenced by pinning defects) into the steady-flow-motion regime. The experimental observation of transverse transport of skyrmions due to topological charge may potentially create many exciting opportunities, such as topological selection. Experiments show that when driven by electric currents, magnetic skyrmions experience transverse motion due to their topological charge — similar to the conventional Hall effect experienced by charged particles in a perpendicular magnetic field.

The formation of soap bubbles from thin films is accompanied by topological transitions. Here we show how a magnetic topological structure, a skyrmion bubble, can be generated in a solid-state system in a similar manner. Using an inhomogeneous in-plane current in a system with broken inversion symmetry, we experimentally \"blow\" magnetic skyrmion bubbles from a geometrical constriction. The presence of a spatially divergent spin-orbit torque gives rise to instabilities of the magnetic domain structures that are reminiscent of Rayleigh-Plateau instabilities in fluid flows. We determine a phase diagram for skyrmion formation and reveal the efficient manipulation of these dynamically created skyrmions, including depinning and motion. The demonstrated current-driven transformation from stripe domains to magnetic skyrmion bubbles could lead to progress in skyrmion-based spintronics.

Magnon interference is a hallmark of coherent magnon interactions. In this work, we demonstrate single-shot magnon interference using up to four magnon pulses in two remotely coupled yttrium iron garnet spheres mediated by a coplanar superconducting resonator. By exciting one YIG sphere with injected microwave pulses, we achieve coherent energy exchange between the two spheres, facilitating their interference processes, including Rabi-like oscillation with a single pulse, constructive and destructive interference with two pulses, and interference peak sharpening with up to four pulses—analogous to diffraction grating in optical interference. The resulting interference patterns can be precisely controlled by changing the frequency detuning and time delay of the magnon pulses. The demonstration of time-domain coherent control of remote magnon interference opens new pathways for advancing coherent information processing through multi-operation, circuit-integrated hybrid magnonic networks. Cavity magnonics aims to make use of magnons, spin waves for coherent information processing. Here, Song et al demonstrate single-shot magnon interference between two remote YIG spheres, showing controlled perfect constructive and destructive interference.

Exploring the limits of spontaneous emission coupling is not only one of the central goals in the development of nanolasers, it is also highly relevant regarding future large-scale photonic integration requiring energy-efficient coherent light sources with a small footprint. Recent studies in this field have triggered a vivid debate on how to prove and interpret lasing in the high- β regime. We investigate close-to-ideal spontaneous emission coupling in GaN nanobeam lasers grown on silicon. Such nanobeam cavities allow for efficient funneling of spontaneous emission from the quantum well gain material into the laser mode. By performing a comprehensive optical and quantum-optical characterization, supported by microscopic modeling of the nanolasers, we identify high- β lasing at room temperature and show a lasing transition in the absence of a threshold nonlinearity at 156 K. This peculiar characteristic is explained in terms of a temperature and excitation power-dependent interplay between zero-dimensional and two-dimensional gain contributions. Here the authors present temperature dependent studies of GaN nanobeam lasers grown on a silicon substrate and demonstrate high- β lasing at room temperature. Comprehensive optical and quantum-optical characterization, complemented by microscopic modeling, of the nanolasers allow identification of lasing behavior.

As an in-plane charge current flows in a heavy metal film with spin–orbit coupling, it produces a torque on and thereby switches the magnetization in a neighbouring ferromagnetic metal film. Such spin–orbit torque (SOT)-induced switching has been studied extensively in recent years and has shown higher efficiency than switching using conventional spin-transfer torque. Here we report the SOT-assisted switching in heavy metal/magnetic insulator systems. The experiments used a Pt/BaFe 12 O 19 bilayer where the BaFe 12 O 19 layer exhibits perpendicular magnetic anisotropy. As a charge current is passed through the Pt film, it produces a SOT that can control the up and down states of the remnant magnetization in the BaFe 12 O 19 film when the film is magnetized by an in-plane magnetic field. It can reduce or increase the switching field of the BaFe 12 O 19 film by as much as about 500 Oe when the film is switched with an out-of-plane field. By virtue of strong spin-orbit coupling, a current-carrying heavy metal may generate a torque on the magnetization of an interfaced ferromagnetic metal. Here, the authors demonstrate how this effect assists the magnetic reversal of ferromagnetic insulators with perpendicular magnetic anisotropy.

The interplay between electronic transport and antiferromagnetic order has attracted a surge of interest as recent studies show that a moderate change in the spin orientation of a collinear antiferromagnet may have a significant effect on the electronic band structure. Among numerous electrical probes to read out such a magnetic order, unidirectional magnetoresistance (UMR), where the resistance changes under the reversal of the current direction, can provide rich insights into the transport properties of spin-orbit-coupled systems. However, UMR has never been observed in antiferromagnets before, given the absence of intrinsic spin-dependent scattering. Here, we report a UMR in the antiferromagnetic phase of aFeRh/Ptbilayer, which undergoes a sign change and then increases strongly with an increasing external magnetic field, in contrast to UMRs in ferromagnetic and nonmagnetic systems. We show that Rashba spin-orbit coupling alone cannot explain the sizable UMR in the antiferromagnetic bilayer and that field-induced spin canting distorts the Fermi contours to greatly enhance the UMR by 2 orders of magnitude. Our results can motivate the growing field of antiferromagnetic spintronics and suggest a route to the development of tunable antiferromagnet-based spintronics devices.

Next-generation terahertz (THz) sources demand lightweight, low-cost, defect-tolerant, and robust components with synergistic, tunable capabilities. However, a paucity of materials systems simultaneously possessing these desirable attributes and functionalities has made device realization difficult. Here we report the observation of asymmetric spintronic-THz radiation in Two-Dimensional Hybrid Metal Halides (2D-HMH) interfaced with a ferromagnetic metal, produced by ultrafast spin current under femtosecond laser excitation. The generated THz radiation exhibits an asymmetric intensity toward forward and backward emission direction whose directionality can be mutually controlled by the direction of applied magnetic field and linear polarization of the laser pulse. Our work demonstrates the capability for the coherent control of THz emission from 2D-HMHs, enabling their promising applications on the ultrafast timescale as solution-processed material candidates for future THz emitters. Terahertz radiation has wide array of potential uses, however, finding robust and tunable sources of terahertz radiation has been challenging. Here, Cong et al demonstrate a room temperature terahertz source composed of a two-dimensional hybrid metal halide and ferromagnetic heterostructure.

Background This study aimed to investigate the morbidity profile and the sociodemographic characteristics of unaccompanied refugee minors (URM) arriving in the region of Bavaria, Germany, between October 2014 and February 2016. Methods The retrospective cross sectional study included 154 unaccompanied refugee minors between 10 and 18 years of age. The data was derived from medical data records of their routine first medical examination in two paediatric practices and one collective housing for refugees in the region of Bavaria, Germany. Results Only 12.3% of all participants had no clinical finding at arrival. Main health findings were skin diseases (31.8%) and mental disorders (25%). In this cohort the hepatitis A immunity was 92.8%, but only 34.5% showed a constellation of immunity against hepatitis B. Suspect cases for tuberculosis were found in 5.8% of the URM. There were no HIV positive individuals in the cohort. Notably, 2 females were found to have undergone genital mutilations. Conclusions The majority of arriving URM appear to have immediate health care needs, whereas the pathologies involved are mostly common entities that are generally known to the primary health care system in Germany. Outbreaks due to hepatitis A virus are unlikely since herd immunity can be assumed, while this population would benefit from hepatitis B vaccination due to low immunity and high risk of infection in crowded housing conditions. One key finding is the absence of common algorithms and guidelines in health care provision to URM.

Although semiconductor excitons consist of a fermionic subsystem (electron and hole), they carry an integer net spin similar to Cooper-electron-pairs. While the latter cause superconductivity by forming a Bose–Einstein-condensate, excitonic condensation is impeded by, for example, a fast radiative decay of the electron-hole pairs. Here, we investigate the behaviour of two electron-hole pairs in a quantum dot with wurtzite crystal structure evoking a charge carrier separation on the basis of large spontaneous and piezoelectric polarizations, thus reducing carrier overlap and consequently decay probabilities. As a direct consequence, we find a hybrid-biexciton complex with a water molecule-like charge distribution enabling anomalous spin configurations. In contrast to the conventional-biexciton complex with a net spin of s =0, the hybrid-biexciton exhibits s =±3, leading to completely different photoluminescence signatures in addition to drastically enhanced charge carrier-binding energies. Consequently, the biexcitonic cascade via the dark exciton can be enhanced on the rise of temperature as approved by photon cross-correlation measurements. Artificial atoms usually constitute an orbital structure for trapped charge carriers. Here, Hönig et al . demonstrate that polarization fields and large charge carrier masses can dilute the common orbital conception and find a hybrid-biexciton molecule that enables anomalous spin configurations.

Coherent spin pumping from an antiferromagnet into a metal occurs at ∼400 gigahertz The discovery of giant magnetoresistance in the mid-1980s demonstrated that magnetic structure can change electric resistivities substantially. Theoretical predictions and experimental demonstration of spin transfer torques in the 1990s demonstrated the inverse effect of injecting spin-polarized electric currents into ferromagnetic metals that could modify magnetic states ( 1 ). In general, injection of spin currents into magnetically ordered systems can excite magnetization dynamics ( 2 ), and magnetization dynamics can induce spin currents in adjacent materials through spin pumping ( 3 ). Coherent spin pumping effects have now been observed with antiferromagnetically ordered materials, as reported on page 160 of this issue by Vaidya et al. ( 4 ) and by Li et al. ( 5 ). These results provide new opportunities for using spintronics phenomena at ultrafast time scales and considerably higher frequencies, exceeding by several orders of magnitude the limitations of ferromagnetic materials.