Co{sub 2}FeAl based magnetic tunnel junctions with BaO and MgO/BaO barriers

Journal Article · Wed Jul 15 00:00:00 EDT 2015 · AIP Advances

DOI:https://doi.org/10.1063/1.4927638· OSTI ID:22492273

Rogge, J.; Schmalhorst, J.; Hütten, A. ^[1]; Hetaba, W. ^[1]; Bouchikhaoui, H.; Stender, P.; Baither, D.; Schmitz, G. ^[2]

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1. Center for Spinelectronic Materials and Devices, Physics Department, Bielefeld University, 33615 Bielefeld (Germany)
2. Institute for Materials Science, Stuttgart University, Heisenbergstrasse 3, 70569 Stuttgart (Germany)

We succeed to integrate BaO as a tunneling barrier into Co{sub 2}FeAl based magnetic tunnel junctions (MTJs). By means of Auger electron spectroscopy it could be proven that the applied annealing temperatures during BaO deposition and afterwards do not cause any diffusion of Ba neither into the lower Heusler compound lead nor into the upper Fe counter electrode. Nevertheless, a negative tunnel magnetoresistance (TMR) ratio of -10% is found for Co{sub 2}FeAl (24 nm) / BaO (5 nm) / Fe (7 nm) MTJs, which can be attributed to the preparation procedure and can be explained by the formation of Co- and Fe-oxides at the interfaces between the Heusler and the crystalline BaO barrier by comparing with theory. Although an amorphous structure of the BaO barrier seems to be confirmed by high-resolution transmission electron microscopy (TEM), it cannot entirely be ruled out that this is an artifact of TEM sample preparation due to the sensitivity of BaO to moisture. By replacing the BaO tunneling barrier with an MgO/BaO double layer barrier, the electric stability could effectively be increased by a factor of five. The resulting TMR effect is found to be about +20% at room temperature, although a fully antiparallel state has not been realized.

• OSTI ID: 22492273
• Journal Information: AIP Advances, Vol. 5, Issue 7; Other Information: (c) 2015 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 2158-3226
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
ANNEALING
AUGER ELECTRON SPECTROSCOPY
BARIUM OXIDES
COMPARATIVE EVALUATIONS
COPPER BASE ALLOYS
DEPOSITION
ELECTRODES
HEUSLER ALLOYS
INTERFACES
IRON ALLOYS
MAGNESIUM OXIDES
MAGNETORESISTANCE
MOISTURE
PHASE STABILITY
SAMPLE PREPARATION
SUPERCONDUCTING JUNCTIONS
TUNNEL EFFECT