Brillouin light scattering studies of planar metallic magnonic crystals

The application of Brillouin light scattering to the study of the spin-wave spectrum of one- and two-dimensional planar magnonic crystals consisting of arrays of interacting stripes, dots and antidots is reviewed. It is shown that the discrete set of allowed frequencies of an isolated nanoelement becomes a finite-width frequency band for an array of identical interacting elements. It is possible to tune the permitted and forbidden frequency bands, modifying the geometrical or the material magnetic parameters, as well as the external magnetic field. From a technological point of view, the accurate fabrication of planar magnonic crystals and a proper understanding of their magnetic excitation spectrum in the GHz range is oriented to the design of filters and waveguides for microwave communication systems

Dissipation characteristics of quantized spin waves in nano-scaled magnetic ring structures

The spatial profiles and the dissipation characteristics of spin-wave quasi-eigenmodes are investigated in small magnetic Ni$_{81}$Fe$_{19}$ ring structures using Brillouin light scattering microscopy. It is found, that the decay constant of a mode decreases with increasing mode frequency. Indications for a contribution of three-magnon processes to the dissipation of higher-order spin-wave quasi-eigenmodes are found

The efficacy and safety of duloxetine in a multidrug regimen for chronic prostatitis/chronic pelvic pain syndrome.

OBJECTIVE To evaluate the efficacy and safety of duloxetine hydrochloride in the treatment of patients affected by chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS). METHODS Thirty-eight CP/CPPS patients completed the National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI) and International Index of Erectile Function-Erectile Function-5 (IIEF-5) questionnaires, uroflowmetry, and evaluation of psychologic status using Hamilton Anxiety Scale (HAM-A) and Hamilton Depression Scale (HAM-D). Patients were randomly assigned to 2 treatments groups. Treatment in group 1 consisted of a simultaneous oral administration of tamsulosin (0.4 mg/d, 60 mg/d), saw palmetto (320 mg/d), and duloxetine (60 mg/d). Treatment in group 2 consisted of tamsulosin (0.4 mg/d) and saw palmetto (320 mg/d). NIH-CPSI and IIEF-5 questionnaires, uroflowmetry, and evaluation of the psychological status were repeated at 16 weeks of follow-up. RESULTS At 16 weeks, a significant improvement in NIH-CPSI pain subscore, NIH-CPSI quality of life subscore, and NIH-CPSI total score were observed in group 1 patients compared with those in group 2 (P <.01, respectively), together with a significant improvement in HAM-A and HAM-D scores (P <.01, respectively). Patients in group 2 showed a significant improvement in NIH-CPSI total score, in the urinary symptoms subscore, and in the HAM-A total score. No significant differences were observed in IIEF-5 scores in the 2 groups. Maximum flow rate significantly increased in both groups. In group 1, 20% of patients stopped the study due to adverse effects. CONCLUSION The use of duloxetine in a multimodal treatment with an alpha-blocker medication and a saw palmetto extract allowed better results in controlling clinical symptoms, psychologic status and quality of life patients affected by CP/CPPS

Propagating spin waves excited by spin-transfer torque: A combined electrical and optical study

Nanocontact spin-torque oscillators are devices in which the generation of propagating spin waves can be sustained by spin transfer torque. In the present paper, we perform combined electrical and optical measurements in a single experimental setup to systematically investigate the excitation of spin waves by a nanocontact spin-torque oscillator and their propagation in a Ni80Fe20 extended layer. By using microfocused Brillouin light scattering we observe an anisotropic emission of spin waves, due to the broken symmetry imposed by the inhomogeneous Oersted field generated by the injected current. In particular, spin waves propagate on the side of the nanocontact where the Oersted field and the in-plane component of the applied magnetic field are antiparallel, while propagation is inhibited on the opposite side. Moreover, propagating spin waves are efficiently excited only in a limited frequency range corresponding to wavevectors inversely proportional to the size of the nanocontact. This frequency range obeys the dispersion relation for exchange-dominated spin waves in the far field, as confirmed by micromagnetic simulations of similar devices. The present results have direct consequences for spin wave based applications, such as synchronization, computation, and magnonics

Competing anisotropies in exchange biased nano-structured thin films

The magnetic anisotropies of a patterned, exchange biased Fe50 Mn50 /Ni80 Fe20 system are studied using ferromagnetic resonance, supplemented by Brillouin light scattering experiments and Kerr magnetometry. The exchange biased bilayer is partially etched into an antidot geometry so that the system approximates a Ni80 Fe20 layer in contact with antidot structured Fe50 Mn50 . Brillouin light scattering measurements of the spin wave frequency dependence on the wave vector reveal a magnonic band gap as expected for a periodic modulation of the magnetic properties. Analysis of the ferromagnetic resonance spectra reveals eightfold and fourfold contributions to the magnetic anisotropy. Additionally, the antidot patterning decreases the magnitude of the exchange bias and modifies strongly its angular dependence. Softening of all resonance modes is most pronounced for the applied magnetic field aligned within 10◦ of the antidot axis, in the direction of the bias. Given the degree to which one can tailor the ground state, the resulting asymmetry at low frequencies could make this an interesting candidate for applications such as selective/directional microwave filtering and multistate magnetic logic

Collective modes for an array of magnetic dots in the vortex state

The dispersion relations for collective magnon modes for square-planar arrays of vortex-state magnetic dots, having closure magnetic flux are calculated. The array dots have no direct contact between each other, and the sole source of their interaction is the magnetic dipolar interaction. The magnon formalism using Bose operators along with translational symmetry of the lattice, with the knowledge of mode structure for the isolated dot, allows the diagonalization of the system Hamiltonian giving the dispersion relation. Arrays of vortex-state dots show a large variety of collective mode properties, such as positive or negative dispersion for different modes. For their description, not only dipolar interaction of effective magnetic dipoles, but non-dipolar terms common to higher multipole interaction in classical electrodynamics can be important. The dispersion relation is shown to be non-analytic as the value of the wavevector approaches zero for all dipolar active modes of the single dot. For vortex-state dots the interdot interaction is not weak, because, the dynamical part (in contrast to the static magnetization of the vortex state) dot does not contain the small parameter, the ratio of vortex core size to the dot radius. This interaction can lead to qualitative effects like the formation of modes of angular standing waves instead of modes with definite azimuthal number known for the insolated vortex state dot