Exceeding 400% tunnel magnetoresistance at room temperature in epitaxial Fe/MgO/Fe(001) spin-valve-type magnetic tunnel junctions
Abstract
Giant tunnel magnetoresistance (TMR) ratios of 417% at room temperature (RT) and 914% at 3 K were demonstrated in epitaxial Fe/MgO/Fe(001) exchange-biased spin-valve magnetic tunnel junctions (MTJs) by tuning growth conditions for each layer, combining sputter deposition for the Fe layers, electron-beam evaporation of the MgO barrier, and barrier interface tuning. Clear TMR oscillation as a function of the MgO thickness with a large peak-to-valley difference of ∼80% was observed when the layers were grown on a highly (001)-oriented Cr buffer layer. Specific features of the observed MTJs are symmetric differential conductance (dI/dV) spectra for the bias polarity and plateau-like deep local minima in dI/dV (parallel configuration) at |V| = 0.2-0.5 V. At 3 K, fine structures with two dips emerge in the plateau-like dI/dV, reflecting highly coherent tunneling through the Fe/MgO/Fe. We also observed a 496% TMR ratio at RT by a 2.24 nm-thick-CoFe insertion at the bottom-Fe/MgO interface.
- Publication:
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Applied Physics Letters
- Pub Date:
- January 2021
- DOI:
- 10.1063/5.0037972
- arXiv:
- arXiv:2011.08739
- Bibcode:
- 2021ApPhL.118d2411S
- Keywords:
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- Condensed Matter - Materials Science
- E-Print:
- 21 pages, 7 figures