Spin-wave amplification and lasing driven by inhomogeneous spin transfer torques

We show that an inhomogeneity in the spin-transfer torques in a metallic ferromagnet under suitable conditions strongly amplifies incoming spin waves. Moreover, at nonzero temperatures the incoming thermally occupied spin waves will be amplified such that the region with inhomogeneous spin transfer torques emits spin waves spontaneously, thus constituting a spin-wave laser. We determine the spin-wave scattering amplitudes for a simplified model and set-up, and show under which conditions the amplification and lasing occurs. Our results are interpreted in terms of a so-called black-hole laser, and could facilitate the field of magnonics, that aims to utilize spin waves in logic and data-processing devices.Comment: 5 pages, 4 figure

Spin-vorticity coupling in viscous electron fluids

We consider spin-vorticity coupling - the generation of spin polarization by vorticity - in viscous two-dimensional electron systems with spin-orbit coupling. We first derive hydrodynamic equations for spin and momentum densities in which their mutual coupling is determined by the rotational viscosity. We then calculate the rotational viscosity microscopically in the limits of weak and strong spin-orbit coupling. We provide estimates that show that the spin-orbit coupling achieved in recent experiments is strong enough for the spin-vorticity coupling to be observed. On the one hand, this coupling provides a way to image viscous electron flows by imaging spin densities. On the other hand, we show that the spin polarization generated by spin-vorticity coupling in the hydrodynamic regime can, in principle, be much larger than that generated, e.g. by the spin Hall effect, in the diffusive regime

Spin-wave amplification and lasing driven by inhomogeneous spin-transfer torques

We show that an inhomogeneity in the spin-transfer torques in a metallic ferromagnet under suitable conditions strongly amplifies incoming spin waves. Moreover, at nonzero temperatures the incoming thermally occupied spin waves will be amplified such that the region with inhomogeneous spin-transfer torques emits spin waves spontaneously, thus constituting a spin-wave laser. We determine the spin-wave scattering amplitudes for a simplified model and setup, and show under which conditions the amplification and lasing occurs. Our results are interpreted in terms of a so-called black-hole laser, and could facilitate the field of magnonics, which aims to utilize spin waves in logic and data-processing devices.</p

Investigation of the ground-state spin inversion in the neutron-rich 47,49Cl isotopes

A first γ -ray study of 47,49Cl spectroscopy was performed at the Radioactive Isotope Beam Factory with 50Ar projectiles at 217 MeV/nucleon, impinging on the liquid hydrogen target of the MINOS device. Prompt deexcitation γ rays were measured with the NaI(Tl) array DALI2+. Through the one-proton knockout reaction 50Ar(p, 2p), a spin assignment could be determined for the low-lying states of 49Cl from the momentum distribution obtained with the SAMURAI spectrometer. A spin-parity Jπ = 3/2+ is deduced for the ground state of 49Cl, similar to the recently studied N = 32 isotope 51K. The evolution of the energy difference E(1/2+ 1 ) − E(3/2+ 1 ) is compared to state-of-the-art theoretical predictions.Ministerio de Ciencia de España, Innovación y Universidades y fondos FEDER. FIS2017-88410-PFondo Nacional de Investigación, Desarrollo e Innovación de Hungría. Proyecto No. K128947.The Office of Nuclear Physics, U.S. Department of Energy. De-sc0018223The United Kingdom Science and Technology Facilities Council (STFC). ST/L005816/1Natural Sciences and Engineering Research Council of Canada (NSERC). SAPIN-2016-00033, SAPIN-2018- 00027 y RGPAS-2018-522453

Identification of a millisecond isomeric state in 129Cd81 via the detection of internal conversion and Compton electrons

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