Erase/restorable asymmetric magnetization reversal in polycrystalline ferromagnetic films

Asymmetric hysteresis loops are generally found in exchange-coupled ferromagnetic/antiferromagnetic layers or composite. Once the film is deposited the magnetization reversal behaviour becomes certain due to the fixed anisotropy of the film. We report an asymmetric magnetization reversal, which is erase/restorable in polycrystalline soft magnetic film. When the film is pre-saturated at a high field in the induced uniaxial easy direction, the asymmetric hysteresis loops with one branch governed by "coherent rotation" and another branch with kink induced by mixed reversal mechanism of "coherent rotation" and "rotation/180 degrees-domain-wall-motion/rotation" are obtained. If the film is presaturated in the induced hard axis, the kink disappears and "normal" hysteresis behaviour is observed instead. Such asymmetric magnetization curve can be restored if the film is pre-saturated in the easy axis again. The observed phenomenon is originated from an embedded second magnetically hard phase which tunes the anisotropy in the film. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4765652

Co-based amorphous thin films on silicon with soft magnetic properties

The present work investigates the emergence of multiple modes in the high-frequency permeability spectrum of Co-Zr-Ta-B amorphous thin films. Amorphous thin films of different thicknesses (t=100-530 nm) were deposited by DC magnetron sputtering. Their static and dynamic soft magnetic properties were investigated to explore the presence of multi-magnetic phases in the films. A two-phase magnetic behavior of the thicker films (≥333 nm) was revealed by the in-plane hysteresis loops. Multiple resonance peaks were observed in the high-frequency permeability spectrum of the thicker films. The thickness dependent multiple resonance peaks below the main ferromagnetic resonance (FMR) can be attributed to the two-phase magnetic behaviors of the films

PwrSoC (integration of micro-magnetic inductors/transformers with active semiconductors) for more than Moore technologies

This paper introduces the concept of power supply on chip (PwrSoC) which will enable the development of next-generation, functionally integrated, power management platforms with applications in dc-dc conversion, gate drives, isolated power transmission and ultimately, high granularity, on-chip, power management for mixed-signal, SOC chips. PwrSoC will integrate power passives with the power management IC, in a 3D stacked or monolithic form factor, thereby delivering the performance of a high-efficiency dc-dc converter within the footprint of a low-efficiency linear regulator. A central element of the PwrSoC concept is the fabrication of power micro-magnetics on silicon to deliver micro-inductors and micro-transformers. The paper details the magnetics on silicon process which combines thin film magnetic core technology with electroplated copper conductors. Measured data for micro-inductors show inductance operation up to 20 MHz, footprints down to 0.5 mm(2), efficiencies up to 93% and dc current carrying capability up to 600 mA. Measurements on micro-transformers show voltage gain of approximately - 1 dB at between 10 MHz and 30 MHz

Controlling the competing magnetic anisotropy energies in FineMET amorphous thin films with ultra-soft magnetic properties

Thickness dependent competing magnetic anisotropy energies were investigated to explore the global magnetic behaviours of FineMET amorphous thin films. A dominant perpendicular magnetization component in the as-deposited state of thinner films was observed due to high magnetoelastic anisotropy energy which arises from stresses induced at the substrate-film interface. This perpendicular magnetization component decreases with increasing film thickness. Thermal annealing at elevated temperature revealed a significant influence on the magnetization state of the FineMET thin films and controlled annealing steps leads to ultra-soft magnetic properties, making these thin films alloys ideal for a wide range of applications

Study of haematological parameters in malaria

Background: Malaria   causing   plasmodia   are   parasites   of   blood   and   hence   induce haematological alterations. The haematological changes that have been reported to accompany malaria include anemia, thrombocytopenia and leucocytosis, leukopenia, mild   to   moderate   atypical   lymphocytosis, monocytosis,   eosinophilia   and neutrophilia.Methods: Total hundred smear positive malaria cases were taken and various hematological parameters and biochemical parameters were studied.Results: Out of 100 smear positive cases, P. vivax was positive in 55 cases while P. falciparum was positive in 45 cases. It was seen in 86.67% of falciparum Malaria patients and in 72.72% of vivax Malaria patients. Severe anemia was seen in 9% of patients. Normocytic normochromic blood picture was the most common type in anaemic patients (51.89%). Thrombocytopenia was seen in 71% of the patients. Mild thrombocytopenia was more common and present in 52% of patients while Severe thrombocytopenia was seen in 19% of cases. In falciparum malaria thrombocytopenia was present in 66.66% of the patients while it was present in 74.54% of the patients in vivax malaria. Total Leucocyte Count was normal in 72% of the patients.Conclusions: Various haematological findings can help in early diagnosis of malaria which is essential for timely and appropriate treatment which can limit the morbidity and prevent further complications

PCB embedded bondwire inductors with discrete thin film magnetic core for power supply in package

This paper details the design, assembly, and detailed characterization of Printed Circuit Board (PCB) embedded thin magnetic film inductor for Power Supply in Package applications. Solenoidal inductors were assembled on copper tracks printed on PCB with wire bonds to complete the copper loop. Further, the solenoid inductors have laminated amorphous soft magnetic thin films embedded between the two conductor layers. The devices have chemically thinned Vitrovac films laminated as core material. Three different designs of solenoid inductors with different number of turns, are assembled and characterized. The assembled PCB inductor measured a highest Quality factor of 8.5 for a 3 turn device at 10 MHz

Tailoring the ultra-soft magnetic properties of sputtered FineMET thin films for high-frequency power applications

This paper presents sputtered FineMET thin films with high saturation magnetic flux density and ultra-soft magnetic properties by maintaining an in-plane magnetization reversal process. The magnetic properties of FineMET thin films were investigated as a function of film thickness (40-517 nm) and annealing temperature (200-400 °C). The hysteresis loop study reveals that the films with low thickness (40 −316 nm) were perpendicularly magnetized in the as-deposited state. The ultra-soft magnetic properties (Hc =3 A/m) of the films were tailored by a thermal annealing process. A high relative permeability (μr ) of 1763 of these films with a good loss performance up to 1 GHz, makes them attractive for high-frequency power applications

Novel high frequency electrical characterization technique for magnetic passive devices

Integrated magnetic components are key elements of the Power Supply on Chip modules. Due to the application requirements, these magnetic devices work at very high frequency and have low inductances. Conventional small-signal tests do not provide all the required information about the magnetic device. Hence, it is important to develop new set-ups to apply large signals to accurately measure the performance of devices under realistic operating conditions, including non-linear core effects. The proposed experimental set-up is suitable to measure the device impedance under different large-signal test conditions, similar to those in the actual converter, since the excitation current can be configured through every winding: ac current up to 0.5 A at frequencies up to 120 MHz and dc bias current up to 2 A through one or both windings. Voltage and current are measured using commercial instrumentation. Due to the characteristics of the probes and the high frequency of the test, the attenuation and delay due to the probes and the experimental set-up have to be taken into account when processing the voltage and current waveforms to calculate the impedances. The compensation test to calculate this attenuation and delay is described. Finally, the proposed set-up is validated by measuring a two-phase coupled inductors micro-fabricated on silicon

High frequency, single/dual phases, large AC/DC signal power characterization for two phase on-silicon coupled inductors

In this work, a new set-up is presented to characterize the large signal electrical parameters of on-Silicon integrated coupled inductors for Power Supply on Chip. The proposed system is suitable to perform the measurements under different large-signal test conditions given by the dc bias current up to 2 A and ac current through one or both windings, with amplitudes ranging from 0 A to 0.5 A at frequencies up to 120 MHz. Since a key issue when measuring at high-frequencies is the error due to the attenuation and time skew between the channels, an additional test is performed to characterize the measurement system and compensate the voltage and current waveforms

Synthesis of CJ-15,208, a novel κ-opioid receptor antagonist

The tryptophan isomers of the cyclic tetrapeptide CJ-15,208, reported to be a kappa opioid receptor (KOR) antagonist [Saito, T.; Hirai, H.; Kim, Y. J.; Kojima, Y.; Matsunaga, Y.; Nishida, H.; Sakakibara, T.; Suga, O.; Sujaku, T.; Kojima, N. J. Antibiot. (Tokyo) 2002, 55, 847–854.], were synthesized to determine the tryptophan stereochemistry in the natural product. A strategy was developed to select linear precursor peptides that favor cyclization using molecular modeling, and optimized cyclization conditions are reported. The optical rotation of the l-Trp isomer is consistent with that of the natural product. Unexpectedly both isomers exhibit similar nanomolar affinity for KOR