Fabrication of Magnetic Tunnel Junctions with a Synthetic Ferrimagnetic Free Layer for Magnetic Field Sensor Applications

作者：Fujiwara Kousuke^*; Oogane Mikihiko; Kou Futoyoshi; Watanabe Daisuke; Naganuma Hiroshi; Ando Yasuo

来源：Japanese Journal of Applied Physics, 2011, 50(1): 013001.

DOI：10.1143/JJAP.50.013001

Magnetic tunnel junctions (MTJs) with a CoFeB/Ru/Ni80Fe20 synthetic ferrimagnetic free layer and an MgO barrier layer were fabricated. The effect of the shape and thickness of the free layer on the magnetic field sensor characteristics was systematically investigated. We achieved a high sensitivity of 4.8%/Oe in the MTJ with a 70-nm-thick Ni80Fe20 layer and an aspect ratio of 1.0. Here, sensitivity is defined as TMR/(2H(k)), where TMR is tunnel magnetoresistance ratio in the MTJ and H-k is a magnetic anisotropy field of the free layer. Furthermore, we successfully increased the detection field range up to 230 Oe while keeping high sensitivity and linearity.

• 出版日期2011-1