Universal helimagnon and skyrmion excitations in metallic, semiconducting and insulating chiral magnets.

Nearly seven decades of research on microwave excitations of magnetic materials have led to a wide range of applications in electronics. The recent discovery of topological spin solitons in chiral magnets, so-called skyrmions, promises high-frequency devices that exploit the exceptional emergent electrodynamics of these compounds. Therefore, an accurate and unified quantitative account of their resonant response is key. Here, we report all-electrical spectroscopy of the collective spin excitations in the metallic, semiconducting and insulating chiral magnets MnSi, Fe1-xCoxSi and Cu2OSeO3, respectively, using broadband coplanar waveguides. By taking into account dipolar interactions, we achieve a precise quantitative modelling across the entire magnetic phase diagrams using two material-specific parameters that quantify the chiral and the critical field energy. The universal behaviour sets the stage for purpose-designed applications based on the resonant response of chiral magnets with tailored electric conductivity and an unprecedented freedom for an integration with electronics.

Comparison of effects of a home exercise programme and a supervised exercise programme for the management of lateral elbow tendinopathy.

BACKGROUND: Home and supervised exercise programmes consisting of stretching and eccentric exercises have been recommended for the management of lateral elbow tendinopathy (LET). No studies have examined their comparative efficacy effectiveness. OBJECTIVE: In this study, whether a home exercise programme is more successful than a supervised exercise programme in treating patients with LET was investigated. METHODS: Patients with unilateral LET for at least 4 weeks were included in this trial. They were sequentially allocated to receive either a home exercise programme or a supervised exercise programme five times a week for 12 weeks. The exercise programme consisted of slow progressive eccentric exercises of wrist extensors and static stretching of the extensor carpi radialis brevis tendon. Outcome measures were pain, using a visual analogue scale, and function, using a visual analogue scale and the pain-free grip strength. Patients were evaluated at baseline, at the end of treatment (week 12), and 3 months (week 24) after the end of treatment. RESULTS: 70 patients met the inclusion criteria. At the end of treatment, there was a decline in pain and a rise in function in both groups compared with baseline (p<0.0005, paired t test). There were significant differences in the reduction of pain and the improvement of function between the groups at the end of treatment and at the 3-month follow up; the supervised exercise programme produced the largest effect (p<0.0005, independent t test). CONCLUSIONS: Supervised exercise programme is superior to home exercise programme to reduce pain and improve function in patients with LET at the end of the treatment and at the follow-up. Further research is needed to confirm our results.

Linearly polarized GHz magnetization dynamics of spin helix modes in the ferrimagnetic insulator Cu2OSeO3.

Linear dichroism - the polarization dependent absorption of electromagnetic waves- is routinely exploited in applications as diverse as structure determination of DNA or polarization filters in optical technologies. Here filamentary absorbers with a large length-to-width ratio are a prerequisite. For magnetization dynamics in the few GHz frequency regime strictly linear dichroism was not observed for more than eight decades. Here, we show that the bulk chiral magnet Cu2OSeO3 exhibits linearly polarized magnetization dynamics at an unexpectedly small frequency of about 2 GHz at zero magnetic field. Unlike optical filters that are assembled from filamentary absorbers, the magnet is shown to provide linear polarization as a bulk material for an extremely wide range of length-to-width ratios. In addition, the polarization plane of a given mode can be switched by 90° via a small variation in width. Our findings shed a new light on magnetization dynamics in that ferrimagnetic ordering combined with antisymmetric exchange interaction offers strictly linear polarization and cross-polarized modes for a broad spectrum of sample shapes at zero field. The discovery allows for novel design rules and optimization of microwave-to-magnon transduction in emerging microwave technologies.

Exchange anisotropy in the skyrmion host GaV4S8.

Using ferromagnetic resonance spectroscopy at 34 GHz we explored the magnetic anisotropy of single-crystalline GaV4S8 in the field-polarized magnetic state. We describe the data in terms of an easy-axis type uniaxial anisotropy with an anisotropy constant [Formula: see text] erg cm-3 at 2 K, corresponding to a relative exchange anisotropy [Formula: see text]%, and about [Formula: see text]erg cm-3 near 11 K, i.e. at temperatures where the skyrmion-lattice phase was recently discovered. The relatively large value of K 1 explains the confinement of the skyrmion tubes to the [Formula: see text] easy axes. A distinct set of resonances in the spectra is attributed to the co-existence of different rhombohedral domains. Complementary broadband spectroscopy demonstrates that non-collinear spin states may sensitively be detected by electron spin resonance techniques.

Room-temperature helimagnetism in FeGe thin films.

Chiral magnets are promising materials for the realisation of high-density and low-power spintronic memory devices. For these future applications, a key requirement is the synthesis of appropriate materials in the form of thin films ordering well above room temperature. Driven by the Dzyaloshinskii-Moriya interaction, the cubic compound FeGe exhibits helimagnetism with a relatively high transition temperature of 278 K in bulk crystals. We demonstrate that this temperature can be enhanced significantly in thin films. Using x-ray scattering and ferromagnetic resonance techniques, we provide unambiguous experimental evidence for long-wavelength helimagnetic order at room temperature and magnetic properties similar to the bulk material. We obtain α intr = 0.0036 ± 0.0003 at 310 K for the intrinsic damping parameter. We probe the dynamics of the system by means of muon-spin rotation, indicating that the ground state is reached via a freezing out of slow dynamics. Our work paves the way towards the fabrication of thin films of chiral magnets that host certain spin whirls, so-called skyrmions, at room temperature and potentially offer integrability into modern electronics.

Treatment of carpal tunnel syndrome with polarized polychromatic noncoherent light (Bioptron light): a preliminary, prospective, open clinical trial.

OBJECTIVE: Our aim was to assess the efficacy of polarized polychromatic noncoherent light (Bioptron light) in the treatment of idiopathic carpal tunnel syndrome. BACKGROUND: Carpal tunnel syndrome is the most common compression neuropathy, but no satisfactory conservative treatment is available at present. METHOD: An uncontrolled experimental study was conducted in patients who visited our clinic from mid-2001 to mid-2002. A total of 25 patients (22 women and three men) with unilateral idiopathic carpal tunnel syndrome, mild to moderate nocturnal pain, and paraesthesia lasting >3 months participated in the study. The average age of the patients was 47.4 years and the average duration of patients' symptoms was 5.2 months. Polarized polychromatic noncoherent light (Bioptron light) was administered perpendicular to the carpal tunnel area. The irradiation time for each session was 6 min at an operating distance of 5-10 cm from the carpal tunnel area, three times weekly for 4 weeks. Outcome measures used were the participants' global assessments of nocturnal pain and paraesthesia, respectively, at 4 weeks and 6 months. RESULTS: At 4 weeks, two patients (8%) had no change in nocturnal pain, six (24%) were in slightly less nocturnal pain, 12 (48%) were much better in regard to nocturnal pain and five (20%) were pain-free. At 6 months, three patients (12%) were slightly better in regard to nocturnal pain, 13 (52%) were much better regarding nocturnal pain, and nine patients (36%) were pain-free. At 4 weeks, four patients (16%) had no change in paraesthesia, five (20%) were slightly better, 13 patients (52%) were much better, and three patients (12%) were without paraesthesia. At 6 months, two patients (8%) had no change in paraesthesia, two (8%) were slightly better, 14 (56%) were much better, and seven (28%) were without paraesthesia. CONCLUSIONS: Nocturnal pain and paraesthesia associated with idiopathic carpal tunnel syndrome improved during polarized polychromatic noncoherent light (Bioptron light) treatment. Controlled clinical trials are needed to establish the absolute and relative effectiveness of this intervention.

Magnetic thin-film insulator with ultra-low spin wave damping for coherent nanomagnonics.

Wave control in the solid state has opened new avenues in modern information technology. Surface-acoustic-wave-based devices are found as mass market products in 100 millions of cellular phones. Spin waves (magnons) would offer a boost in today's data handling and security implementations, i.e., image processing and speech recognition. However, nanomagnonic devices realized so far suffer from the relatively short damping length in the metallic ferromagnets amounting to a few 10 micrometers typically. Here we demonstrate that nm-thick YIG films overcome the damping chasm. Using a conventional coplanar waveguide we excite a large series of short-wavelength spin waves (SWs). From the data we estimate a macroscopic of damping length of about 600 micrometers. The intrinsic damping parameter suggests even a record value about 1 mm allowing for magnonics-based nanotechnology with ultra-low damping. In addition, SWs at large wave vector are found to exhibit the non-reciprocal properties relevant for new concepts in nanoscale SW-based logics. We expect our results to provide the basis for coherent data processing with SWs at GHz rates and in large arrays of cellular magnetic arrays, thereby boosting the envisioned image processing and speech recognition.

Imaging of cationic multifunctional liposome-mediated delivery of COX-2 siRNA.

Liposomes are a useful means of delivering molecular targeting agents such as small interfering RNA (siRNA) to downregulate specific pathways important in cancer growth and progression. The ability to non-invasively image these carriers is important to ascertain their delivery within the tumor. As cyclooxygenase-2 (COX-2) is an important therapeutic target in cancer, we investigated loading COX-2-specific siRNA into cationic liposomes containing MR contrast agents for imaging delivery in cancer cells and tumors. COX-2 and GAPDH siRNA, as well as Magnevist or Feridex, were loaded directly into the liposomes. These lipoplexes were used for cell transfection of the poorly differentiated and highly metastatic breast cancer cell line MDA-MB-231. PEGylated liposomes loaded with Feridex and fluorescently labeled COX-2 siRNA were used for in vivo delivery of lipoplexes in MDA-MB-231 breast cancer xenografts in female SCID mice. Transient transfection assays demonstrated potent and specific downregulation of the COX-2 protein in cells in culture. Tail vein injections of PEGylated COX-2 lipoplexes resulted in intratumoral delivery of siRNA. Biodistribution studies showed significant localization in the lung, liver and kidney at 24 h. These data demonstrate the feasibility of liposomal-mediated delivery of COX-2-specific siRNA to downregulate COX-2 in cancer cells, and multi-modality imaging of the delivery of specific siRNA in tumors.