Tunnel Magnetoresistance Over 100% in MgO-Based Magnetic Tunnel Junction Films With Perpendicular Magnetic L1$_{0}$-FePt Electrodes

Abstract

Perpendicular L1 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> -FePt/MgO/Fe/L1 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> -FePt magnetic tunnel junction (MTJ) films with the (001) texture were successfully developed to obtain a large tunnel magnetoresistance (TMR) above 100 % at room temperature. The TMR ratio in the L1 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> -FePt/MgO/Fe/L1 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> -FePt MTJ was strongly dependent on the Fe interfacial layer thickness. The lattice mismatch between the MgO(001) barrier layer and the L1 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> -FePt(001) layer is too large for the MgO barrier layer to grow epitaxially on the L1 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> -FePt(001) layer. The insertion of the Fe interfacial layer improves the quality of the MgO(001) barrier layer and achieves an epitaxy in the L1 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> -FePt/MgO/Fe/L1 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> -FePt stack. As a result, the optimization of the Fe interfacial layer thickness is a key to obtain the large TMR ratio in the MgO-based MTJ with the L1 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> -FePt electrodes.