Wannier-Stark ladder spectrum of Bloch oscillations of magneto-dipole spin waves in graded 1D magnonic crystals

This is the author accepted manuscript. The final version is available from AIP Publishing via the DOI in this recordWe have used the method of Wannier functions to calculate the frequencies and profiles of spin waves localised in one-dimensional (1D) magnonic crystals due to a gradient in the bias magnetic field. This localisation of spin waves is analogous to the phenomenon of Bloch oscillations of quantum-mechanical electrons in crystals in a uniform electric field. As a convenient yet realistic model, we consider backward volume magnetostatic spin waves (BVMSWs) in a film of yttriumiron garnet (YIG) in a bias magnetic field comprising spatially uniform, cosine and gradient contributions. The spin-wave spectrum is shown to have the characteristic form of a WannierStark ladder. The analytical results are verified using those obtained using numerical micromagnetic simulations. The physics of spin-wave Bloch oscillations combines the topics of magnonic crystals and graded magnonic index – the two cornerstones of modern magnonics.Engineering and Physical Sciences Research Council (EPSRC)European Union Horizon 202

Magnetic excitations in Dy/Y superlattices as seen via inelastic neutron scattering

Measurements of the spin excitations propagating normal to the interfaces in Dy/Y superlattices using neutron inelastic scattering are presented. For a given magnon momentum, a neutron-scattering spectrum shows multiple peaks at different energies, which indicates discrete energy spectra. The results are compared with theoretical calculations developed here to describe magnetic excitations in rare-earth superlattices. The theory accounts for Ruderman-Kittel-Kasuya-Yosida (RKKY) and Dzyaloshinsky-Moriya interactions in incommensurate helicoidal structures and achieves a quantitative agreement with the experimental data. This work demonstrates that neutron inelastic scattering can be used for systematic studies of the exchange interactions and spin dynamics in nanomagnetic systems over wide areas of the Brillouin zone

METHODOLOGICAL APPROACHES TO THE ESTIMATION OF INDIVIDUAL OCCUPATIONAL RISK TAKING INTO ACCOUNT INDICATORS OF LIFE QUALITY

Authors offer to make changes to technique of the estimation of life quality with three blocks of professional and nonprofessional risk factors: index of observance of requirements of sanitary legislations; index of way of life and index of social well-being. The index of observance of requirements of sanitary legislations pays off by result of an expert estimation of a workplace taking into account aggravating (absence of certification of workplaces, industrial inspection; insufficiency of the area and volume of premises; absence of ventilation, repairs, work and rest modes; neediness of good-quality potable water, sanitary-household premises, first-aid sets of the first medical aid; absence of system of informing of workers about an existing professional risk and ways of its decrease etc.) and normalizing factors (presence of complexes intrareplaceable and after a labor shift medical rehabilitations etc.). The index of way of life is offered to be counted taking into account major individual behavioral and biological factors of risk of death rate and invalidity in Russia: smoking, abusing alcohol, irrational food (in particular, the uses less than 400 g vegetables and fruit in day), insufficient physical activity, raised index of weight of a body, psychoemotional stress, raised levels of cholesterol and glucose in whey of blood, arterial pressure, burdened heredity. The index of social well-being pays off as the one-numerical indicator considering social and economic and socially-psychological factors: indicator of size of wages, indicator of satisfaction health, working conditions, work as a whole, life as a whole, an indicator of the individual importance of factors of psychological overload. Authors of article suggest to add an existing technique of an estimation of an indicator of the individual importance of psychological overload factors with indicators actual in modern industrial conditions: socially-psychological adaptation, degree of emotional burning out, quality of life. The estimation of quality of life can serve in this system to one of the most significant after experience medical and biologic criteria of an estimation of an individual professional risk

Antiferromagnetism in a Fe50Pt40Rh10 thin film investigated using neutron diffraction

The temperature-dependent magnetic structure of a 200 nm thick single-crystalline film of Fe50Pt40Rh10 was studied by unpolarized and polarized neutron diffractions. By applying structure factor calculations, a detailed model of the magnetic unit cell was developed. In contrast to former studies on bulk samples, our experimental results show that the film remains in an antiferromagnetic state throughout the temperature range of 10-450 K. Remarkably, it can be demonstrated that the antiferromagnetic structure undergoes a smooth transition from a dominant out-of-plane order with the magnetic moments orientated in-plane to an in-plane order with the magnetic moments orientated perpendicular to the film plane. Theoretically this can be explained by the existence of two competing anisotropy contributions with different temperature dependencies

Neutron scattering measurements of magnetic excitations in Gd/Y superlattices

Neutron inelastic scattering has been used to measure the magnetic excitations as a function of applied magnetic field in an antiferromagnetically coupled Gd/Y superlattice. The excitations were measured along the c-axis, which is parallel to the normal of the interfaces and the sample growth direction. Dispersive spin waves were unambiguously detected on the application of a magnetic field. The spin waves are shown to renormalize with field following a basic model drawn from standard spin wave theory. The model required no free parameters aside from an initial amplitude. (C) 2010 American Institute of Physics. [doi:10.1063/1.3428425