Low frequency 1/f barrier noise has been investigated in sputtered MgO magnetic tunnel junctions (MTJs) with a tunneling magnetoresistance ratio of up to 330% at room temperature. The lowest normalized noise parameter α of the tunnel barrier reaches 2.5 × 10-12-2.1 × 10 -11 μm2, which is comparable to that found in MTJs with the MgO barrier grown by MBE or electron-beam evaporation. This normalized barrier noise is almost bias independent in the voltage range of up to ±1.2 V. The low noise level and high voltage stability may reflect the high quality of the sputtered MgO with a uniform distribution of defects in the MgO layer.
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JFF thanks Z. Diao for useful discussions. This work was supported by SFI as part of the MANSE Project No. 2005/IN/1850 and was conducted under the framework of the INSPIRE program, funded by the Irish Government's Program for Research in Third Level Institutions, Cycle 4, National Development Plan 2007–2013.