Search results for "FOS"

Domain wall motion in a diffusive weak ferromagnet

2019

We study the domain wall motion in a disordered weak ferromagnet, induced by injecting a spin current from a strong ferromagnet. Starting from the spin diffusion equation describing the spin accumulation in the weak ferromagnet, we calculate the force and torque acting on the domain wall. We also study the ensuing domain wall dynamics, and suggest a possible measurement method for detecting the domain wall motion via measuring the additional resistance.

Thermalization of hot electrons via interfacial electron-magnon interaction

2019

Recent work on layered structures of superconductors (S) or normal metals (N) in contact with ferromagnetic insulators (FI) has shown how the properties of the previous can be strongly affected by the magnetic proximity effect due to the static FI magnetization. Here we show that such structures can also exhibit a new electron thermalization mechanism due to the coupling of electrons with the dynamic magnetization, i.e., magnons in FI. We here study the heat flow between the two systems and find that in thin films the heat conductance due to the interfacial electron-magnon collisions can dominate over the well-known electron-phonon coupling below a certain characteristic temperature that ca…

Magnetization Dynamics in Proximity-Coupled Superconductor-Ferromagnet-Superconductor Multilayers

2020

In this work, magnetization dynamics is studied in superconductor/ferromagnet/superconductor three-layered films in a wide frequency, field, and temperature ranges using the broad-band ferromagnetic resonance measurement technique. It is shown that in presence of both superconducting layers and of superconducting proximity at both superconductor/ferromagnet interfaces a massive shift of the ferromagnetic resonance to higher frequencies emerges. The phenomenon is robust and essentially long-range: it has been observed for a set of samples with the thickness of ferromagnetic layer in the range from tens up to hundreds of nanometers. The resonance frequency shift is characterized by proximity-…

Magnetoelectric effects in superconductor/ferromagnet bilayers

2018

We demonstrate that the hybrid structures consisting of a superconducting layer with an adjacent spin-textured ferromagnet demonstrate the variety of equilibrium magnetoelectric effects originating from coupling between the conduction electron spin and superconducting current. By deriving and solving the generalized Usadel equation which takes into account the spin-filtering effect we find that a supercurrent generates spin polarization in the superconducting film which is non-coplanar with the local ferromagnetic moment. The inverse magnetoelectric effect in such structures is shown to result in the spontaneous phase difference across the magnetic topological defects such as a domain wall …

Mapping of the magnetic field to correct systematic effects in a neutron electric dipole moment experiment

2021

Experiments dedicated to the measurement of the electric dipole moment of the neutron require outstanding control of the magnetic-field uniformity. The neutron electric dipole moment (nEDM) experiment at the Paul Scherrer Institute uses a Hg199 co-magnetometer to precisely monitor temporal magnetic-field variations. This co-magnetometer, in the presence of field nonuniformity, is, however, responsible for the largest systematic effect of this measurement. To evaluate and correct that effect, offline measurements of the field nonuniformity were performed during mapping campaigns in 2013, 2014, and 2017. We present the results of these campaigns, and the improvement the correction of this eff…

The charm-quark contribution to light-by-light scattering in the muon (−2) from lattice QCD

2022

We compute the hadronic light-by-light scattering contribution to the muon $g-2$ from the charm quark using lattice QCD. The calculation is performed on ensembles generated with dynamical $(u,d,s)$ quarks at the SU(3)$_{\rm f}$ symmetric point with degenerate pion and kaon masses of around 415 MeV. It includes the connected charm contribution, as well as the leading disconnected Wick contraction, involving the correlation between a charm and a light-quark loop. Cutoff effects turn out to be sizeable, which leads us to use lighter-than-physical charm masses, to employ a broad range of lattice spacings reaching down to 0.039 fm and to perform a combined charm-mass and continuum extrapolation.…

Trinatriumfosfaattitankkauksen vaikutuksia mieskestävyysurheilijoiden kestävyyssuorituskykyyn

1999

Maizes rauga adenīna biosintēzes ceļa mutāciju ietekme uz oksidatīvā un karstuma stresu izturību.

2021

Maizes raugs ir nozīmīgs modeļorganisms, lai praktiski pētītu adenīna biosintēzes ceļa mutāciju ietekmi uz oksidatīvā un karstuma stresu izturību, nepievienojot tiem barības vielas. Bakalaura darba ietvaros pētīta adenīna biosintēzes ceļa mutantu ietekme uz oksidatīvo un karstuma stresu, katalāzes un glikozes 6-fosfāta dehidrogenāzes enzīmu aktivitāte. Vispirms atrasti optimālie ilgumi šūnu pakļaušanai stresiem, tad noskaidrots, ka purīna un slāpekļa badināšana palielina stresa izturību neatkarīgi no mutācijas vietas adenīna sintēzes ceļā. Iegūtie rezultāti norāda, ka katalāze uzrāda augstāku aktivitāti pie augstākas oksidatīvā stresa izdzīvotības W303 un Δade, Δade2 celmiem, bet ne Δade8, …

Bayesian semiparametric long memory models for discretized event data

2020

We introduce a new class of semiparametric latent variable models for long memory discretized event data. The proposed methodology is motivated by a study of bird vocalizations in the Amazon rain forest; the timings of vocalizations exhibit self-similarity and long range dependence. This rules out Poisson process based models where the rate function itself is not long range dependent. The proposed class of FRActional Probit (FRAP) models is based on thresholding, a latent process. This latent process is modeled by a smooth Gaussian process and a fractional Brownian motion by assuming an additive structure. We develop a Bayesian approach to inference using Markov chain Monte Carlo and show g…

An Inverse Problem for the Relativistic Boltzmann Equation

2020

We consider an inverse problem for the Boltzmann equation on a globally hyperbolic Lorentzian spacetime $(M,g)$ with an unknown metric $g$. We consider measurements done in a neighbourhood $V\subset M$ of a timelike path $\mu$ that connects a point $x^-$ to a point $x^+$. The measurements are modelled by a source-to-solution map, which maps a source supported in $V$ to the restriction of the solution to the Boltzmann equation to the set $V$. We show that the source-to-solution map uniquely determines the Lorentzian spacetime, up to an isometry, in the set $I^+(x^-)\cap I^-(x^+)\subset M$. The set $I^+(x^-)\cap I^-(x^+)$ is the intersection of the future of the point $x^-$ and the past of th…