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We report a study on the growth temperature dependent phase formation and its magnetic property in Mn‐doped Ge nanowires (NWs) fabricated at temperature (TG) varying from 600 to 900 °C using vapor–liquid–solid technique. Structural and magnetic measurements on the nanowires reveal that Mn are not homogeneously distributed in Ge‐matrix, but atomic clusters (Mn‐rich regions) are formed in lightly doped Ge matrix (GeMn‐matrix) at 600 °C. Upon increasing TG, Ge3Mn5 compound starts to nucleate in expense of atomic clusters following the migration of Mn from GeMn‐matrix. At 900 °C, only precipitates of Ge3Mn5 in cluster‐free Ge‐matrix are found.

We have fabricated Fe3O4/p-Si heterojunction using pulsed laser deposition technique and explored its electro-magnetic transport properties. The heterojunction exhibits backward rectifying property at all temperatures, and appraisal of giant junction magnetoresistance (JMR) is observed at room temperature (RT). Conspicuously, the variation and sign change of JMR as a function of electric field is observed at RT. The backward rectifying behavior of the device is ascribed to the highly doped p-type (p++) semiconducting nature of Fe3O4, and the origin of electric field (voltage) dependence of magnetoresistance is explained proposing electronic band diagram of Fe3O4/SiO2/p-Si heterojunction. This interesting result may have importance to integrate Si-based magnetoresistance sources in multifunctional spintronic devices.

Er-doped SnO 2 nanoparticles were synthesized with varying Er concentration by a sol-gel method. X-ray diffraction (XRD) and high-resolution transmission electron microscopic studies reveal the crystalline nature of the nanoparticles and the crystallite size decreases with the increase of Er concentration in SnO 2 . For higher Er concentration, the evolution of Er 2 O 3 as a secondary phase is detected. The X-ray photoelectron spectroscopy (XPS) study depicts the existence of 4d level of Er along with a partially filled 4f state. Infrared photoluminescence (IRPL) measurement shows a strong emission peak at 1540 nm due to Er doping in the SnO 2 nanoparticles, which quenches after 3 at% of Er concentration. Magnetic measurement reveals the antiferromagnetic (AFM) behavior of the Er-doped samples, though there is an increase in magnetic moment with increase in Er concentration. Undoped SnO 2 shows a weak ferromagnetic interaction, which could be due to the presence of anionic defects (O vacancy). a status solidi www.pss-a.com physica ß

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