Andreev reflection in ferrimagnetic CoFe2O4/SrRuO3 spin filters

We have performed point contact spectroscopy measurements on a sample constituted by a metallic ferromagnetic oxide (SrRuO_3) bottom electrode and a tunnel ferrimagnetic (CoFe_2O_4) barrier. Andreev reflection is observed across the tunnel barrier. From the comparison of Andreev reflection in SrRuO3 and across the CoFe_2O_4 barrier we infer that the ferrimagnetic barrier has a spin filter efficiency not larger than +13%. The observation of a moderate and positive spin filtering is discussed in the context of the microstructure of the barriers and symmetry-related spin filtering effects.Comment: 13 pages, 5 figures. To appear in Phys. Rev. B

The magnetization of epitaxial nanometric CoFe2O4(001) layers

We have studied the magnetic anisotropy of nanometric CoFe2O4 (CFO) thin films grown on (100) SrTiO3 (STO) substrates. It has been found that epitaxial substrate-induced compressive strain makes the normal-to-film axis harder than the in-plane directions. In agreement with some previous reports, the magnetization loops are found to display a characteristic shrinking at low fields. Detailed structural and microstructural analyses, together with a modeling of the magnetization loops, revealed that the microstructure of the films, namely, the coexistence of a continuous CFO and a distribution of pyramidal CFO huts emerging from the surface, are responsible for this peculiar feature. We argue that this behavior, which significantly impacts the magnetic properties, could be a general trend of spinel films grow on (001) STO substrates

The magnetization of epitaxial nanometric CoFe2O4(001) layers

We have studied the magnetic anisotropy of nanometric CoFe2O4 (CFO) thin films grown on (100) SrTiO3 (STO) substrates. It has been found that epitaxial substrate-induced compressive strain makes the normal-to-film axis harder than the in-plane directions. In agreement with some previous reports, the magnetization loops are found to display a characteristic shrinking at low fields. Detailed structural and microstructural analyses, together with a modeling of the magnetization loops, revealed that the microstructure of the films, namely, the coexistence of a continuous CFO and a distribution of pyramidal CFO huts emerging from the surface, are responsible for this peculiar feature. We argue that this behavior, which significantly impacts the magnetic properties, could be a general trend of spinel films grow on (001) STO substrates

Is Internet Use Associated with Anxiety in Patients with and at Risk of Cardiomyopathy?

OBJECTIVE: The aim of the study was to determine the relation between online health information seeking behavior and anxiety level among a sample of patients with manifested cardiomyopathy or at risk for cardiomyopathy. METHODS: The research is a cross-sectional study conducted among 104 patients with cardiomyopathy diagnosis and patients at risk for cardiomyopathy. Patients completed 3 different questionnaires: Use of Internet Health Information questionnaire about the use of Internet, Short Form SF-12 items questionnaire on quality of life, and State-Trait Anxiety Inventory measuring general anxiety levels. RESULTS: Forty-eight patients had a diagnosis of primary or secondary cardiomyopathy, and 56 patients, with conditions predisposing to cardiomyopathy. Eighty-five percent of the considered population is surfing the Internet to obtain nonspecific information about health in general, and the 65% use it to look specifically for heart disease. For both groups of patients with cardiomyopathy and at risk for cardiomyopathy, online health information seeking behavior is associated with substantially lower state anxiety levels (P = .041). CONCLUSION: Web use, as a source of health information, has been shown to be associated with anxiety reduction in patients with or at risk for cardiomyopathy, suggesting that Internet technology can be a useful instrument due to its informational power and its potentially therapeutic value

Strain-induced stabilization of new magnetic spinel structures in epitaxial oxide heterostructures.

We report here on the growth of NiFe2O4 epitaxial thin films of different thickness (3 nm ¿ t ¿ 32 nm) on single crystalline substrates having spinel (MgAl2O4) or perovskite (SrTiO3) structure. Ultrathin films, grown on any of those substrates, display a huge enhancement of the saturation magnetization: we will show that partial cationic inversion may account for this enhancement, although we will argue that suppression of antiparallel collinear spin alignment due to size-effects cannot be excluded. Besides, for thicker films, the magnetization of films on MAO is found to be similar to that of bulk ferrite; in contrast, the magnetization of films on STO is substantially lower than bulk. We discuss on the possible mechanisms leading to this remarkable difference of magnetization

Follow-Up with Exercise Test of Effort-Induced Ventricular Arrhythmias Linked to Ryanodine Receptor Type 2 Gene Mutations

The aim of this study was to assess exercise test results and efficacy of therapy with a β blocker (acebutolol) in ryanodine receptor type 2 (RyR2) mutation carriers with documented ventricular arrhythmias (VAs) and long-term follow-up. Twenty RyR2 mutation carriers belonging to 8 families and regularly followed at our center were analyzed using a study protocol involving electrocardiography, exercise tests off and on β-blocker therapy, 2-dimensional echocardiography, and signal-averaged electrocardiography. Off-therapy exercise testing triggered the onset of VAs at different heart rates (mean 132 ± 13 beats/min) with various patterns that worsened while exercising and disappeared immediately after stopping. The most severe VAs detected were nonsustained ventricular tachycardia in 35% and ventricular couplets in 35%. In the remaining subjects single ventricular premature beats were recorded. In 15% of patients single monomorphic ventricular premature beats were detected and identified to be linked to RyR2 mutations owing to the presence of sudden deaths of their family members and subsequent family screening. Acebutolol made the VAs disappear completely in 20% of subjects and decreased their complexity in 50%, whereas it did not change VAs appreciably in 30% of patients with less complex VAs. After 11 ± 8 years of follow-up 2 patients developed syncope. In conclusion, exercise testing was a fundamental tool for assessing the clinical phenotype and efficacy of therapy in RyR2 mutation carriers and therapy with acebutolol led in most subjects to a decreased complexity of the arrhythmic pattern or to complete suppression

Solid-State Color Centers for Single-Photon Generation

Single-photon sources are important for integrated photonics and quantum technologies, and can be used in quantum key distribution, quantum computing, and sensing. Color centers in the solid state are a promising candidate for the development of the next generation of single-photon sources integrated in quantum photonics devices. They are point defects in a crystal lattice that absorb and emit light at given wavelengths and can emit single photons with high efficiency. The landscape of color centers has changed abruptly in recent years, with the identification of a wider set of color centers and the emergence of new solid-state platforms for room-temperature single-photon generation. This review discusses the emerging material platforms hosting single-photon-emitting color centers, with an emphasis on their potential for the development of integrated optical circuits for quantum photonics