Structural, electrical, and magnetic properties of Mo1−xFexO2 (x=0–0.05) thin films grown by pulsed laser ablation

Abstract

We report the growth of undoped and Fe (2 and 5 at%) doped molybdenum oxide thin films on c-plane of sapphire substrate using pulsed laser ablation. X-ray diffraction results show that the films are oriented in (100) direction and have monoclinic structure based on MoO 2 phase as also supported by Raman spectroscopy. The x-ray photoelectron spectroscopy reveals chemical state of Fe is +2, which favors the substitutional occupancy of Fe ion in the MoO 2 matrix.The room temperature resistivity of all the films are very low (~100 µΩcm). The Fe doped samples show ferromagnetic behavior at room temperature.

X-ray absorption and magnetic circular dichroism characterization of Mo1–xFexO2 (x = 0–0.05) thin films grown by pulsed laser ablation

“…It has been shown previously [5] that the energy region between 529 and 538 eV (marked by A 1 -D 1 ) is due to O 2p hybridization with Mo 4d states which form the bottom of the conduction band, while the region between 539 and 550 eV (marked by E 1 ) can be assigned to O 2p-Mo 5sp hybridized states and above 550 eV, the spectrum arises due to the O 2p states that extend to Mo higher orbitals. Since Mo ions exist in Mo 4+ (4d 2 ) and Mo 5+ /Mo 6+ (4d 1 /4d 0 ) oxidation states and the Mo 4+ component increases at the cost of Mo 5+/6+ ions after Fe-doping [9], the observed pre-edge features A 1 -D 1 are due to the 4d-2p(O) hybridization, which is influenced strongly by distortion of MoO 6 octahedra. For the octahedral environment of the molybdenum, the crystal field splitting leads to a separation of the lower part of the conduction band into t 2g and e g symmetry band, and distortion of the octahedra in MoO x leads to further splitting of the t 2g and e g states into A 1 ,B 1 and C 1 ,D 1 components, respectively.…”

“…All the samples were characterized by x-ray diffraction, bulk magnetization, and resistivity measurements. The details of sample preparation and characterization are described elsewhere [5,9]. The NEXAFS and XMCD measurements were performed at the ESRF's ID08 beamline, which uses an APPLE II type undulator giving ∼100% circular polarization.…”

X-ray diffraction and photoelectron spectroscopy study of swift heavy ion irradiated Mn/p-Si structure

“…The cleaning standard has already been calibrated by monitoring the surface carbon from XPS measurements for an optimum duration of 5-10 min of the sputtering [e.g. [11]]. For XRD data Philips PW-1710 diffractometer has been used with Cu K alpha source (l = 1.54060 Å ).…”

Preparation and photoelectric properties of semiconductor MoO2 micro/nanospheres with wide bandgap

“…However, Rogers et al [28] and Shi et al [29] reported the measurement results of MoO 2 powders, which show a positive temperature coefficient of resistance in the temperature range from 0 to 300 K, characteristics of a metallic sample. Prakash et al [30] performed the temperature dependent electrical resistivity measurements using standard fourprobe technique, which shows metal to insulator transition at temperature of 101 K for the MoO 2 samples. The different curve of temperature vs. resistance could be ascribed to the nonstoichiometric nature of the samples [30].…”

“…Prakash et al [30] performed the temperature dependent electrical resistivity measurements using standard fourprobe technique, which shows metal to insulator transition at temperature of 101 K for the MoO 2 samples. The different curve of temperature vs. resistance could be ascribed to the nonstoichiometric nature of the samples [30]. Fig.…”