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

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 statemore » has not been realized.« less
Authors:
; ;  [1] ;  [1] ;  [2] ; ; ; ;  [3]
  1. Center for Spinelectronic Materials and Devices, Physics Department, Bielefeld University, 33615 Bielefeld (Germany)
  2. (Austria)
  3. Institute for Materials Science, Stuttgart University, Heisenbergstrasse 3, 70569 Stuttgart (Germany)
Publication Date:
OSTI Identifier:
22492273
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Advances; Journal Volume: 5; Journal Issue: 7; Other Information: (c) 2015 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
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