Magnetoresistance in 82Ni-Fe/Al-Al2O3/Co Junction. Dependence of the Tunneling Conductance on the Angle between the Magnetizations of Two Ferromagnetic Layers.

Development of the magnetic tunnel junction MRAM at IBM: From first junctions to a 16-Mb MRAM demonstrator chip

“…Attempts to apply this artificial tunnel barrier technique to magnetic tunnel junctions, though initially slow to succeed, eventually resulted in demonstrations at room temperature of an effect of the size earlier expected. First, in 1991, Miyazaki and co-workers at Tohoku University reported NiFe/Al-Al 2 O 3 /Co junctions with TMRs of 2.7% at room temperature [23,24]. This was a significantly higher percentage than earlier roomtemperature results, but far lower than expectations.…”

Bias voltage and temperature dependence of magnetotunneling effect

“…Magnetic-tunnel junctions ͑MTJs͒ are emerging as a new class of magnetoresistive ͑MR͒ devices. [1][2][3][4][5][6][7] MTJs have demonstrated a number of technical advantages over the existing giant magnetoresistance ͑GMR͒ devices. Metallic GMR structures are inherently highly conductive, so a large current density is required to generate enough voltage signal.…”

“…This technique separates the magnetic response of the top electrode from that of the bottom, and enables us to attain saturated antiparallel configurations of the junction. After the deposition, a lithographical patterning procedure was used to fabricate the MTJ devices as small as 1ϫ1 m. 2 The details of this process have been described elsewhere. [5][6][7] The blanket multilayer films are examined by a vibrating-sample magnetometer at room temperature after the deposition.…”

“…The simple two-current model does not take into consideration the effects of electron band structure, tunnel barrier transmission, and spin-flipping excitations into consideration, and thus, predicts no bias voltage dependence for the magnetoresistance. Experimenters, [1][2][3][4] however, have always observed a substantial decrease in MR with the application of bias. The differential resistance in parallel ͑solid͒ and antiparallel ͑dashed͒ states as well as the MR of one of our junctions are plotted versus dc bias in Fig.…”