An alignment-free sensing module for the positioning system based on tunneling magnetoresistive (TMR) sensors with an absolute-incremental-integrated scale is demonstrated. The sensors of the proposed system for both lines consist of identical layer stacks; therefore, all sensors can be fabricated in identical processes from thin film deposition to device patterning on a single substrate. Consequently, the relative position of the sensors can be predefined at the lithography stage and the alignment error between sensors caused by the manual installation is completely eliminated. Different from the existing sensing scheme for incremental lines, we proposed to utilize the magnetic tunnel junctions with a perpendicular anisotropy reference layer and an in-plane anisotropy sensing layer. The sensors are placed parallel to the scale plane with magnetization of the sensing layer in the plane, which show the capability of polarity detection for the absolute line and reveal sinusoidal output signal for the incremental line. Furthermore, due to the large signal of TMR, the working distance can be further improved compared with conventional sensors. In addition, the cost of the positioning system is expected to be lowered, since all the sensors are fabricated in the same process without extra installation. Our design may pave a new avenue for the positioning system based on a magnetic detection scheme.
This work applied an anisotropic magneto-resistance effect for studying the spin–orbit torque (SOT)-driven magnetization switching in an antiferromagnetic heavy alloy/ferromagnet, PtMn/Co bilayer, under y-type SOT geometry. The tailorable magneto-structural ordering of PtMn provides an additional dimension to study the interplay among SOT efficiency, the interfacial spin configuration, and the y-type SOT switching. The results reveal that the SOT efficiency of PtMn, effective field generated by current, can be enhanced via forming the L10 (antiferromagnetic) phase after annealing; however, the efficiency appears to be less sensitive to the interfacial spin configuration. On the other hand, the critical current for the y-type SOT switching is even strongly associated with the PtMn/Co interfacial spin configuration. The lowest (highest) critical current is yielded when Co is antiferromagnetically (ferromagnetically) coupled to PtMn through the exchange bias. Engineering the interfacial spin configuration may provide an effective strategy to promote the critical current for the SOT device.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.