The desire to maximize the sensitivity of read/write heads (and thus the information density) of magnetic storage devices has stimulated interest in the discovery and design of new magnetic materials exhibiting magnetoresistance. Recent discoveries include the 'colossal' magnetoresistance in the manganites and the enhanced magnetoresistance in low-carrier-density ferromagnets. An important feature of these systems is that the electrons involved in electrical conduction are different from those responsible for the magnetism. The latter are localized and act as scattering sites for the mobile electrons, and it is the field tuning of the scattering strength that ultimately gives rise to the observed magnetoresistance. Here we argue that magnetoresistance can arise by a different mechanism in certain ferromagnets--quantum interference effects rather than simple scattering. The ferromagnets in question are disordered, low-carrier-density magnets where the same electrons are responsible for both the magnetic properties and electrical conduction. The resulting magnetoresistance is positive (that is, the resistance increases in response to an applied magnetic field) and only weakly temperature-dependent below the Curie point.

Magnetic semiconductors are attracting high interest because of their potential use for spintronics, a new technology which merges electronics and manipulation of conduction electron spins. (GaMn)As and (GaMn)N have recently emerged as the most popular materials for this new technology. While Curie temperatures are rising towards room temperature, these materials can only be fabricated in thin film form, are heavily defective, and are not obviously compatible with Si. We show here that it is productive to consider transition metal monosilicides as potential alternatives. In particular, we 1 report the discovery that the bulk metallic magnets derived from doping the narrow gap insulator FeSi with Co share the very high anomalous Hall conductance of (GaMn)As, while displaying Curie temperatures as high as 53 K. Our work opens up a new arena for spintronics, involving a bulk material based only on transition metals and Si, and which we have proven to display a variety of large magnetic field effects on easily measured electrical properties.

The environmental degradation and hazard to human life caused by the depletion of fossils fuels and the urgent need for sustainable energy sources to meet the rising demand in energy has led to the exploration of novel materials that are environmentally friendly, low cost and less hazardous to human life for energy storage application using the green chemistry approach.Herein, we report on the transformation of the readily abundant pine cone biomass into porous carbon via KOH activation and carbonization at 800 °C as electrode materials supercapacitor.The porous carbon material exhibited a mesoporous framework with a specific surface area of

Landau-Fermi liquid theory, with its pivotal assertion that electrons in metals can be simply understood as independent particles with effective masses replacing the free electron mass, has been astonishingly successful. This is true despite the Coulomb interactions an electron experiences from the host crystal lattice, lattice defects and the other approximately 10(22) cm(-3) electrons. An important extension to the theory accounts for the behaviour of doped semiconductors. Because little in the vast literature on materials contradicts Fermi liquid theory and its extensions, exceptions have attracted great attention, and they include the high-temperature superconductors, silicon-based field-effect transistors that host two-dimensional metals, and certain rare-earth compounds at the threshold of magnetism. The origin of the non-Fermi liquid behaviour in all of these systems remains controversial. Here we report that an entirely different and exceedingly simple class of materials-doped small-bandgap semiconductors near a metal-insulator transition-can also display a non-Fermi liquid state. Remarkably, a modest magnetic field functions as a switch which restores the ordinary disordered Fermi liquid. Our data suggest that we have found a physical realization of the only mathematically rigorous route to a non-Fermi liquid, namely the 'undercompensated Kondo effect', where there are too few mobile electrons to compensate for the spins of unpaired electrons localized on impurity atoms.

The LiMn1.5Ni0.5O4 spinel is an important lithium ion battery cathode material that has continued to receive major research attention because of its high operating voltage (∼4.8 V). This study interrogates the impact of microwave irradiation on the Mn(3+) concentration and electrochemistry of the LiMn1.5Ni0.5O4 spinel. It is shown that microwave is capable of tuning the Mn(3+) content of the spinel for enhanced electrochemical performance (high capacity, high capacity retention, excellent rate capability, and fast Li(+) insertion/extraction kinetics). This finding promises to revolutionize the application of microwave irradiation for improved performance of the LiMn1.5Ni0.5O4 spinel, especially in high rate applications.

Manganese phosphate (Mn(PO) hexagonal micro-rods and (Mn(PO) with different graphene foam (GF) mass loading up to 150mg were prepared by facile hydrothermal method. The characterization of the as-prepared samples proved the successful synthesis of Mn(PO) hexagonal micro-rods and Mn(PO)/GF composites. It was observed that the specific capacitance of Mn(PO)/GF composites with different GF mass loading increases with mass loading up to 100mg, and then decreases with increasing mass loading up to 150mg. The specific capacitance of Mn(PO)/100mg GF electrode was calculated to be 270Fg as compared to 41Fg of the pristine sample at a current density of 0.5Ag in a three-electrode cell configuration using 6M KOH. Furthermore, the electrochemical performance of the Mn(PO)/100mg GF electrode was evaluated in a two-electrode asymmetric cell device where Mn(PO)/100mg GF electrode was used as a positive electrode and activated carbon (AC) from coconut shell as a negative electrode. AC//Mn(PO)/100mg GF asymmetric cell device was tested within the potential window of 0.0-1.4V, and showed excellent cycling stability with 96% capacitance retention over 10,000 galvanostatic charge-discharge cycles at a current density of 2Ag.

Few-layer graphene was synthesized on a nickel foam template by chemical vapour deposition (CVD). The resulting three-dimensional (3D) graphene was loaded with nickel oxide nanostructures using the successive ionic layer adsorption and reaction (SILAR) technique. The composites were characterized and investigated as electrode material for supercapacitors. Raman spectroscopy measurements on the sample revealed that the 3D graphene consisted of mostly few layers, while X-ray diffractometry (XRD) and scanning electron microscopy (SEM) revealed the presence of nickel oxide. The electrochemical properties were investigated using cyclic voltammetry, electrochemical impedance spectroscopy and potentiostatic charge-discharge in aqueous KOH electrolyte. The novelty of this work is the use of the 3D porous cell structure of the nickel foam which allows for the growth of highly conductive graphene and subsequently provides support for uniform adsorption of the NiO onto the graphene. The NF-G/NiO electrode material showed excellent properties as a pseudocapacitive device with a high specific capacitance value of 783 Fg -1 at a scan rate of 2 mVs -1 . The device also exhibited excellent cycle stability, with 84% retention of the initial capacitance after 1,000 cycles. The results demonstrate that composites made using 3D graphene are versatile and show considerable promise as electrode materials for supercapacitor applications.

Highlights •NiCo/NiCoMn-mixed hydroxides, ternary NiCo-MnO 2 nanostructures were successfully synthesised. •The samples were used as electrodes for electrochemical supercapacitor in 1 M KOH. •The electrode materials exhibit good charge storage capability on both regions. •Assembled NiCo-MnO 2 /C-FP hybrid supercapattery displays high electrochemical performance.