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...