Spin gapless semiconductors are interesting novel class of materials by embracing both magnetism and semiconducting. Its potential application in future spintronics requires realization in thin film form. In this letter, we report a successful growth of spin gapless Mn 2 CoAl films on thermally oxidized Si substrates by magnetron sputtering deposition. The films deposited at 673K are well oriented to (001) direction and display a uniform-crystalline surface. Magnetotransport measurements on the oriented films reveal a semiconducting-like resistivity, small anomalous Hall conductivity and linear magnetoresistance (MR) representative of the transport signatures of spin gapless semiconductors. The magnetic properties of the films have also been investigated and compared to that of bulk Mn 2 CoAl, with small discrepancy induced by the composition deviation.------------------------------a) Author to whom correspondence should be addressed. . In this letter, we report the growth of oriented Mn 2 CoAl films on thermally oxidized Si substrates using magnetron sputtering.Magnetotransport measurements on the oriented films revealed a semiconducting-like resistivity, small Hall conductivity and linear magnetoresistance indicative of the transport features of SGS.We have deposited a series of Mn 2 CoAl films on thermally oxidized Si substrates using magnetron sputtering system with the base pressure of below 5×10 -5 Pa. The optimized sample we chose for present study is deposited under an Ar pressure of 0.2Pa while the substrate was kept at 673K with dc power of 30W. The typical thickness of the film determined by the stylus profile is about 200-nm-thick under a deposition rate of ~4 Å/s. The structure was determined by X-ray diffraction (XRD) using the Cu-Kα radiation. The composition and morphology of the film were examined by scanning electron microscope (SEM) equipped with an energy-dispersive X-ray spectroscopy (EDX). The magnetic and transport measurements were performed using a superconducting quantum interference device magnetometer (MPMS, Quantum Design) and Physics property measurement system (PPMS, Quantum Design), respectively. The electronic band structure is calculated by employing the coherent potential approximation (CPA) The sign change of ( ) xx T  slope is commonly observed in semimetals or narrow-gap semiconductors where atomic disorder, defects or nonstoichiometry gives rise to impurity levels governing low temperature conduction. 11,12 In our case, the general shape of ( ) xx T  is characteristics of semimetals or doped semiconductors which can be described by an thermal activation model with a small energy gap. 13As shown in the inset of Fig. 2(a), the conductivity is well approximated by a simple model:, where 0  indicates possible nonstoichiometry generated conduction at low temperatures. The best parameter fit yields an energy gap of 90meVThe magnetoresistance (MR) in Fig. 2 , just equivalent to the slope, is actually a temperature independent value. We plot the Hall conductivity as a funct...

This paper describes the fabrication and characterization of copper nano-clusters prepared by a simple one-step electrodeposition process on platinum microelectrode, and the application for nitrate determination. The one-step electrodepostion process was performed by chronoamperometry scan in acidic copper sulphate electrolyte directly. The SEM and electrochemical examination showed that the morphologies and microstructures of deposited copper layers can be precisely controlled by using different deposition voltages. It was found that the copper layer is porous when the deposition voltage is higher than -500 mV, and this porous layer has a larger effective surface area compared with the corresponding smooth flat copper layer deposited under voltage less than -300 mV. Under the optimized deposition voltage, copper clusters constructed by uniform nanoparticles with an average diameter of about 100 nm can be obtained. The mechanism of electrodeposition process for this method was also speculated. The copper layers deposited under different voltages are used in a series of tests in order to evaluate their performance for nitrate sensing. The experimental results reveal that the microelectrode modified by fixed potential deposition under -700 mV had a higher sensitivity of 39.31 μA/mmolL−1 for nitrate detection within the concentration ranging from 0.1 mmolL−1 to 4.0 mmolL−1.

In this study, we present the experimental observation that polycrystalline Mn2+xFe1−xGa (x = −0.2, 0, 0.2, 0.4) compounds can be synthesized to be D019-type (Ni3Sn-type) hexagonal structure with space group P63/mmc. A giant exchange bias field up to 1.32 kOe was achieved in hexagonal Mn2FeGa alloy at 5 K. A cluster glass state is confirmed by ac susceptibility measurement under different driving frequencies. Interestingly, robust horizontal and vertical shifts in magnetic hysteresis loop were simultaneously observed at 5 K under high cooling field up to 90 kOe. The large exchange bias is originated from the large exchange anisotropy between cluster glass phase and ferrimagnetic matrix. The vertical shift is thought to be attributed to the incomplete reversal of frozen cluster spins.

Site preference of doped Mn ions in CoCr2−xMnxO4 (x = 0–2) series has been derived separately from structure and magnetic measurement. It shows that parts of the doped Mn ions occupy the A (Co) sites when x < 0.5. And then, it takes the two B (Cr) sites in turn before and after x = 1.3. This site preference behavior results in a role conversion of the magnetic contributors and, thus, leads to the composition dependent magnetic compensation. Temperature induced compensation and negative magnetization have also been found in several samples, which is attributed to the large energy barrier between the ferromagnetic and antiferromagnetic spin arrangement. A structure transition from cubic to tetragonal symmetry has been detected.