Vortex domain structures and dc current dependence of magneto-resistances in magnetic tunnel junctions

• 来源期刊: 中国物理（英文版）
• 关键词: magnetic tunnel junction tunnel magnetorisistance spin-electron transport magnonassisted tunnelling vortex domain structure
• 年，卷（期）: 2004,（9）
• 页码范围: 1553-1559
• 页数: 7页
• 语种: 英文

摘要

Microfabrication and the magneto-transport characteristics of the magnetic tunnel junctions (MTJs) with a spin-valve-type structure of Ta (5nm)/Ni7gFe21 (25nm)/Ir22Mn78 (12nm)/Co75Fe25 (4nm)/Al(0.8nm) oxide/Co75Fe25(4nm)/Ni7gFe21 (20nm)/Ta(5nm) were investigated in this paper. A series of experimental data measured with a MTJ was used to verify a magnon-assisted tunnelling model and theory. Furthermore, a micromagnetics simulation shows that the butterfly-like vortex domain structures can be formed under a current-induced Oersted field, which decreases the net magnetization values of the ferromagnetic electrodes under a large dc current (i.e., in high voltage regimes). It is one of the main reasons for the tunnel magnetoresistance ratios to decrease significantly at high voltage biasing.