FERROMAGNETIC TUNNEL JUNCTION, MAGNETORESISTIVE EFFECT ELEMENT AND SPINTRONICS DEVICE IN WHICH SAID FERROMAGNETIC TUNNEL JUNCTION IS USED, AND METHOD OF MANUFACTURING FERROMAGNETIC TUNNEL JUNCTION

摘要

The present invention addresses the problem of achieving an unprecedentedly high tunnel magnetic resistance (TMR) ratio using a barrier layer in which an MgAl₂O₄ type insulator material having a spinel structure is used. The problem can be overcome by a ferromagnetic tunnel junction in which the barrier layer comprises a cubic nonmagnetic material having a spinel structure, and in which both of two vertically adjacent ferromagnetic layers of the barrier layer comprise a Co₂FeAl Heusler alloy. Preferably, the nonmagnetic material comprises an oxide of an Mg_1–xAl_x (0 x ≤ 1) alloy, and tunnel magnetic resistance is 250–34000% inclusive at room temperature.