Controlling domain configuration of the sensing layer for magnetic tunneling junctions by using exchange bias

Abstract

The control of magnetic domain formation and fluctuations in the sensing layer is important to progress for low noise in magnetic tunnel junction sensors. We studied the effect of exchange bias on the domain structure in micro-patterned Permalloy (Py: Ni80Fe20) sensing layer. We deposited single Py films, and Pt48Mn52/Py films, where the latter showed exchange bias. By controlling the thickness of Py, Pt48Mn52 (15nm)/Py (t=235 nm) showed a small coercivity and exchange bias of 7 Oe. After micro-fabrication into circular pillars 80 µm in diameter, we measured the domain structure by Magneto Optical Kerr Effect (MOKE) microscopy. MOKE images showed that single Py pillars have a simple closure domain, where the domain wall at the center moved with the applied field. The exchange-biased Py pillars exhibited a more complicated structure, but with fixed domains at the center region due to the exchange bias overcoming the magnetostatic energy. The uniform rotation of magnetization at the center of the sample is promising for decreasing the domain hopping magnetic noise.

Surface Roughness Influence on Néel-, Crosstie, and Bloch-Type Charged Zigzag Magnetic Domain Walls in Nanostructured Fe Films

“…Comprehensive knowledge of the magnetic domain structures is also necessary from an applied point of view [ 18 ], as domain structure investigations provide information about the energetic balance among the interactions that stabilize the ferromagnetic structure, such as magnetostatic, exchange, and anisotropy energy. So, the study of magnetic domain structures is important, and they are continuously the object of analysis and research [ 19 , 20 , 21 , 22 , 23 ]. Indeed, the control of magnetic domain walls in differently shaped materials such as thin films [ 24 ], nanoparticles [ 25 ], nanowires [ 26 ], nanodots [ 27 ], etc., is the subject of numerous investigations for the development of functional materials for scientific and technological applications.…”

Exchange bias effect of current Joule thermally modulated inverted vertical (Co/Pt) n/Co/IrMn nanomultilayers

“…在文章的最后一部分, 我们讨论一下在磁敏传 感器的应用中变化的交换偏置场如何影响磁敏 传感器的线性磁场范围和灵敏度等关键性能参 数 [26,27,32] . I n P r e s s 改变可实现对磁敏传感器的关键性能参数的调控 [33] .…”