Room-temperature ferromagnetic ordering in Mn-doped ZnO thin films grown by pulsed laser deposition

Abstract

The ferromagnetic ordering in Mn-doped ZnO thin films grown by pulsed laser deposition (PLD) as a function of oxygen pressure and substrate temperature has been investigated. Room-temperature ferromagnetic behaviors in the Mn-doped ZnO films grown at 700°C and 800°C under 10 ÿ1 torr in oxygen pressure were found, whereas ferromagnetic ordering in the films grown under 10 ÿ3 torr disappeared at 300 K. The large positive magnetoresistance (MR), ;10%, was observed at 5 K at low fields and small negative MR was observed at high fields, irrespective of oxygen pressure. In particular, anomalous Hall effect (AHE) in the Mn-doped ZnO film grown at 700°C under 10 ÿ1 Torr has been observed up to 210 K. In this work, the observed AHE is believed to be further direct evidence demonstrating that the Mn-doped ZnO thin films are ferromagnetic.

Room temperature ferromagnetism in nanocrystalline Ni-doped ZnO synthesized by co-precipitation

“…The methanol was then evaporated and the mixture was placed in a closed aluminum crucible for sintering at 400 1C for 4 h in its dissolving vapour atmosphere in order to provide partial oxygen deficit. After that, the yield was well mixed by an agate mortar and pestle, cold pressed (at about 750 MPa) into a tablet, and annealed in the same crucible for crystallisation at 600 1C for 8 h. The samples mainly consist of Ni-doped ZnO and might be with traces of C and H; both of them support the possible appearance of RT-FM properties [22,23]. The samples denoted by their Ni content level relative to Zn: 1.0%Ni, 4.3%Ni, 7.4%Ni, and 22.5%Ni.…”

Optical and Magnetic Properties of Zn1–xMnxO Nanorods Grown by Chemical Vapor Deposition

“…In general, polycrystalline ceramics processed at temperatures below 700 °C exhibit the room-temperature FM order ,,,− and at higher annealing temperatures ( T > 700 °C) ,,− ,− become paramagnetic (PM), anti-FM, or spin-glass. For Mn-doped ZnO thin films prepared by RF-magnetron sputtering − and pulsed laser deposition, ,,,,− most of them show the room-temperature FM order. For nanostructured samples (such as nanoparticles, nanowires, nanorods, tetrapods, etc.…”

Structural and magnetic properties of Mn-doped ZnO powders

“…The magnetic behavior of Mn-doped ZnO (ZnO:Mn) has been studied extensively, and different magnetic behaviors, like spin glass [6], paramagnetism [7,8], antiferromagnetism [6], and ferromagnetism (FM) have been all reported [9][10][11][12]. These results show that the magnetization of ZnO:Mn is strongly dependent on the preparation method and procedure, and seems to be sensitive to the crystalline structure and the concentration of oxygen vacancies and defects.…”