Wide range and tunable linear TMR sensor using two exchange pinned electrodes

A magnetic tunnel junction sensor is proposed, with both the detection and the reference layers pinned by IrMn. Using the differences in the blocking temperatures of the IrMn films with different thicknesses, crossed anisotropies can be induced between the detection and the reference electrodes. The pinning of the sensing electrode ensures a linear and reversible output. It also allows tuning both the sensitivity and the linear range of the sensor. The authors show that the sensitivity varies linearly with the ferromagnetic thickness of the detection electrode. It is demonstrated that an increased thickness leads to a rise of sensitivity and a reduction of the operating range.

[1]  D. Lacour,et al.  On the use of exchange biased top electrodes in magnetic tunnel junctions , 2004 .

[2]  Leonel Sousa,et al.  Detection of 130nm magnetic particles by a portable electronic platform using spin valve and magnetic tunnel junction sensors , 2008 .

[3]  A. Panchula,et al.  Magnetically engineered spintronic sensors and memory , 2003, Proc. IEEE.

[4]  John Q. Xiao,et al.  Bias dependence of tunneling magnetoresistance on ferromagnetic electrode thickness , 2003 .

[5]  J. Kools,et al.  Magnetoresistance in Ni80Fe20/Cu/Ni80Fe20/Fe50Mn50 spin valves with low coercivity and ultrahigh sensitivity , 1994 .

[6]  William J. Gallagher,et al.  Exchange-biased magnetic tunnel junctions and application to nonvolatile magnetic random access memory (invited) , 1999 .

[7]  Xiufeng Han,et al.  Temperature-dependent Mn-diffusion modes in CoFeB- and CoFe-based magnetic tunnel junctions: Electron-microscopy studies , 2007 .

[8]  M. Hehn,et al.  Tunnel barrier parameters and magnetoresistance in the parabolic band model , 2001 .

[9]  K. Ju,et al.  Quantitative interpretation of the magnetoresistive response (amplitude and shape) of spin valves with synthetic antiferromagnetic pinned layers , 2000 .

[10]  40% tunneling magnetoresistance after anneal at 380 °C for tunnel junctions with iron-oxide interface layers , 2001 .

[11]  Yiming Huai,et al.  Spin-valve thermal stability: The effect of different antiferromagnets , 2000 .

[12]  A. Schuhl,et al.  Using antiferromagnetic/ferromagnetic bilayers as detection layers in magnetic tunnel junctions , 2003 .

[13]  P. Freitas,et al.  Exchange enhancement and thermal anneal in Mn76Ir24 bottom-pinned spin valves , 2001 .

[14]  P. P. Freitas,et al.  Dependence of tunneling magnetoresistance on ferromagnetic electrode thickness and on the thickness of a Cu layer inserted at the Al2O3/CoFe interface , 1999 .

[15]  C. Yoon,et al.  Thermal stability of the exchanged biased CoFe/IrMn electrode for the magnetic tunnel junction as a function of CoFe thickness , 2002 .

[16]  C.P.O Treutler,et al.  Magnetic sensors for automotive applications , 2001 .

[17]  Y. Huai,et al.  CoFe/IrMn exchange biased top, bottom, and dual spin valves , 2000 .

[18]  A. Kamijo,et al.  Effect of Milling Depth of the Junction Pattern on Magnetic Properties and Yields in Magnetic Tunnel Junctions , 2002 .

[19]  S. Zoll,et al.  GMR angle detector with an artificial antiferromagnetic subsystem (AAF) , 1997 .

[20]  Kazuhiro Saito,et al.  Influence of crystal structure and oxygen content on exchange-coupling properties of IrMn/CoFe spin-valve films , 1999 .

[21]  Jin Xie,et al.  Detection of DNA labeled with magnetic nanoparticles using MgO-based magnetic tunnel junction sensors , 2008 .

[22]  J. M. Daughton,et al.  GMR and SDT sensor applications , 2000 .