Reversible spin storage in metal oxide—fullerene heterojunctions

We show that hybrid MnOx/C60 heterojunctions can be used to design a storage device for spin-polarized charge: a spin capacitor. Hybridization at the carbon-metal oxide interface leads to spin-polarized charge trapping after an applied voltage or photocurrent. Strong electronic structure changes, including a 1-eV energy shift and spin polarization in the C60 lowest unoccupied molecular orbital, are then revealed by x-ray absorption spectroscopy, in agreement with density functional theory simulations. Muon spin spectroscopy measurements give further independent evidence of local spin ordering and magnetic moments optically/electronically stored at the heterojunctions. These spin-polarized states dissipate when shorting the electrodes. The spin storage decay time is controlled by magnetic ordering at the interface, leading to coherence times of seconds to hours even at room temperature

Discrete Hall resistivity contribution from Néel skyrmions in multilayer nanodiscs

Magnetic skyrmions are knot-like quasiparticles. They are candidates for non-volatile data storage in which information is moved between fixed read and write terminals. The read-out operation of skyrmion-based spintronic devices will rely on the electrical detection of a single magnetic skyrmion within a nanostructure. Here we present Pt/Co/Ir nanodiscs that support skyrmions at room temperature. We measured the Hall resistivity and simultaneously imaged the spin texture using magnetic scanning transmission X-ray microscopy. The Hall resistivity is correlated to both the presence and size of the skyrmion. The size-dependent part matches the expected anomalous Hall signal when averaging the magnetization over the entire disc. We observed a resistivity contribution that only depends on the number and sign of skyrmion-like objects present in the disc. Each skyrmion gives rise to 22 ± 2 nΩ cm irrespective of its size. This contribution needs to be considered in all-electrical detection schemes applied to skyrmion-based devices. Not only the area of Néel skyrmions but also their number and sign contribute to their Hall resistivity

Exploring Frequency of Event Reporting as Perceived by Intensive Care Units’ Nurses in Sultanate of Oman: A quality improvement project

Objectives: Little is known about the factors that affect the perceived frequency of event reporting among healthcare workers especially registered nurses working in Oman. This study aimed to find out whether fatigue, workload, burnout, and work environment as independent variables have a relationship with frequency of event reporting as dependent variable and to what extent the aforementioned independent variables predict the frequency of event reporting between nurses working in different intensive care units in selected hospitals in Oman. Methods: This study used a cross-sectional research design. Also this study used standardized questionnaires which are hospital survey on patient safety culture, fatigue assessment scale, maslach burnout inventory-human services survey, NASA task load index, and practice environment scale of the nursing work index. Registered nurses working in intensive care units participated in this study from two referral hospitals in Oman during the period between June and September 2018. Results: A total of 270 nurses were included in this study (response rate: 90%). There was a statistically significant positive relationship between personal accomplishment and the frequency of event reporting (r = 0.132, p < 0.05). Regression analysis showed that nurses’ feedback and communication about errors predicted the frequency of events reporting between intensive care units’ nurses in Oman (R2 = 0.214, adjusted R2 = 0.046; F = 12.82, p < 0.01). Conclusion: Personal accomplishment and feedback and communication about error of intensive care units’ nurses had positive impact on perceived frequency of event reporting whereas no relationship found between fatigue, workload, work environment and frequency of event. Strategies need to be in place in health organizations to encourage nurses to report errors. Keywords: Burnout; Intensive care units’ nurses; Fatigue; frequency of event reporting; Work environment

Comparing the performance of bipolar and unipolar switching frequency to drive DC-AC Inverter

The inverter is a device that is used as an interface between the photovoltaic energy and the grid. The harmonic and distortion of the output current, and efficiency of the inverter are the main issues. This paper presents a model of Sinusoidal Pulse Width Modulation (SPWM) methods of unipolar and bipolar inverters in MATLAB and Psim software. A numerical model of the LC filter is derived in order to design and test the DC-AC inverter. The SPWM control is created by comparing triangle signal (a carrier waveform) and a reference signal (a sine waveform) whose frequency is the desired frequency. The simple circuit is used to characterize the scheme of SPWM techniques in order to obtain the pure output voltage and reduce the harmonic component. Empirical results show that the unipolar switching scheme is used in widespread a commercial PV inverter in order to have the flexibility to choose a filter and reduce the harmonic components. The switching frequency of the Sunny Boy inverter is found around 15 kHz and its transformer is estimated. Unipolar switching SPWM is very useful in low switching frequency than bipolar switching SPWM. The output voltage and current in both techniques have been analyzed in frequency and time domains

Direct measurement of spin polarization in ferromagnetic-C₆₀ interfaces using point-contact Andreev reflection

An important step has been developed combining the potential of spintronics with organic electronics to reveal the promising field of molecular spintronics, which can offer more flexibility, higher recyclability, and low-production costs compared with inorganic devices. Room temperature magnetoresistance (MR) of 5% has been obtained from C 60 spin valves with the structure Co(20 nm)/Al 2 O 3 (1.2 nm)/C 60 (5-60 nm)/Py(20 nm)/Al(1.5 nm). We observe an asymmetric dependence at low temperatures of the MR with voltage, and surprisingly with the magnetic field as well. This behavior has been attributed to the organic interface formed at the junction, which results in a change of the ferromagnet's spin polarization. The spin polarization at the organic-ferromagnetic interface is extracted by measuring the bias dependence of the conductance of a metallic-superconducting point contact and analyzed the spectra with the modified Blonder-Tinkham-Klapwijk theory. Point-contact Andreev reflection measurements reveal that the Co-C 60 possess spin polarization of 30% ± 1%, compared with 40% ± 1% for our Co films without C 60 . This could account for the asymmetry of the MR in spin valves incorporating C 60 and the need for an alumina spacer to maximize the MR

Measuring the spin-polarization power of a single Chiral molecule

The electronic spin filtering capability of a single chiral helical peptide is measured. A ferromagnetic electrode source is employed to inject spin-polarized electrons in an asymmetric single-molecule junction bridging an α-helical peptide sequence of known chirality. The conductance comparison between both isomers allows the direct determination of the polarization power of an individual chiral molecule