Regensburg 2010 – scientific programme

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MA: Fachverband Magnetismus

MA 33: Poster II

MA 33.93: Poster

Friday, March 26, 2010, 11:00–14:00, Poster B1

temperature dependence of transport properties of Co-Fe-B/MgO/Co-Fe-B magnetic tunnel junctions — •Ayaz Arif Khan, Jan Schmalhorst, and Günter Reiss — Thin films and physics of Nano structures, Department of Physics, Bielefeld university, P. O. Box 100131, 33501 Bielefeld germany.

We have performed a systematic analysis of the voltage and temperature dependence of the tunneling magnetoresistance (TMR) in Co-Fe-B/MgO/Co-Fe-B magnetic tunnel junctions (MTJs) with barrier thickness d_MgO between 1.8 and 4 nm. All the junctions show a comparable TMR of about 300 % at low temperature with low bias voltage. Both the junction resistance and magnetoresistance decreases with inceasing temperature or bias voltage. In the bias voltage range of ± 500 mV and temperature range of 13-330 K the strongest decrease of TMR with either increase in bias voltage (of about 98 % ) or increase in temperature (of about 94 % ) was observed for MTJ with 4.0 nm thick barrier. whereas for d_MgO= 1.8 nm the smallest drop of 51 % with increase in voltage and 43 % with rise of temperature was found. MTJs with 2.1 nm and 3.0 nm displayed an intermediate behaviour. This behaviour was analyzed in the framework of recently suggested models for the bias and temperature dependent transport. Especially, the influence of unpolarized and polarized hopping conductance will be discussed.