Investigation on the formation process of single-crystalline GaOx barrier in Fe/GaOx/MgO/Fe magnetic tunnel junctions. (27th September 2017)

• Record Type: Journal Article
• Authors: Krishna, N S; Doko, N; Matsuo, N; Saito, H; Yuasa, S
• Is Part Of: Journal of physics. Volume 50:Number 43(2017)
• Publication Date: 2017-09-27
• Subjects: magnetic tunnel junction -- tunnelling magnetoresistance -- gallium oxide -- epitaxial structure -- solid phase epitaxy; Physics -- Periodicals; 530
• DOI: 10.1088/1361-6463/aa861b
• Languages: English
• ISSNs: 0022-3727

Abstract

Abstract: We have grown Fe(0 0 1)/GaO x (0 0 1)/MgO(0 0 1)/Fe(0 0 1) magnetic tunnel junctions (MTJs) with or without in situ annealing after the deposition of GaO x layer and performed structural characterizations by focusing on the formation process of the single-crystalline GaO x . It was found that, even without the in situ annealing, the as-grown GaO x grown on the MgO was mostly single-crystalline except near the surface region (amorphous). The crystallization temperature of the amorphous region was reduced from 500 °C down to 250 °C by depositing the Fe upper electrode (poly-crystalline). It was clarified that the crystallization of the amorphous region near the Fe/GaO x interface caused the realignments of the crystal grains in the poly-crystalline Fe upper electrode, and, as a result, the fully epitaxial Fe/GaO x /MgO/Fe structure is eventually formed. All the MTJs showed high tunneling magnetoresistance ratios (about 100%) at room temperature, which was almost independent of the formation temperature of the single-crystalline GaO x .