Abstract
The effect of a laminated structure on Conetic films made with sputtering deposition is investigated for application in micro magnetic flux concentrators. It is demonstrated that even with the total magnetic thickness being several micrometers, laminated magnetic films can exhibit significantly reduced coercivity and saturation field compared to single-layer films with the same total magnetic thickness. On the micrometer level, reduction of stress and magnetostriction should be the major reason for significantly improved softness of laminated Conetic films, while cross-layer magnetostatic coupling is also helpful. The improved softness is available not only at room temperature but also at low temperatures. Therefore, with laminated micro magnetic flux concentrators applied in magnetic sensors, the improved softness due to the laminated structure should yield improved reversibility and sensitivity of magnetic sensors at room temperature or low temperatures.
Highlights
Magnetic sensors based on magnetic tunnel junctions (MTJs) have exhibited high sensitivity owing to the high magnetoresistance ratio of MTJs and optimized structures of the sensors, showing great potential in terms of application.1 One of the various techniques to further increase the sensitivity is adding magnetic flux concentrators to MTJ based magnetic sensors, where the magnetic flux concentrators can be external elements attached to the sensor chips or microscale films deposited on the chips.2–7 Micro magnetic flux concentrators have a smaller footprint, and their shape, size, and position can be precisely controlled using modern fabrication technology
The effect of a laminated structure on Conetic films made with sputtering deposition is investigated, and it is demonstrated that deposited laminated magnetic films can stay very soft even with the total magnetic thickness being several micrometers, and they can be suitable for application in micro magnetic flux concentrators
The results imply that on the micrometer level, reduction of stress and magnetostriction should be the major reason for significantly improved softness of laminated Conetic films, while cross-layer magnetostatic coupling is helpful
Summary
Magnetic sensors based on magnetic tunnel junctions (MTJs) have exhibited high sensitivity owing to the high magnetoresistance ratio of MTJs and optimized structures of the sensors, showing great potential in terms of application. One of the various techniques to further increase the sensitivity is adding magnetic flux concentrators to MTJ based magnetic sensors, where the magnetic flux concentrators can be external elements attached to the sensor chips or microscale films deposited on the chips. Micro magnetic flux concentrators have a smaller footprint, and their shape, size, and position can be precisely controlled using modern fabrication technology. Research work by Egelhoff et al showed that significantly improved softness can be achieved in laminated Conetic (Ni77Fe14Cu5Mo4) films with a total magnetic thickness of 400 nm, where the Conetic alloy has the potential to be tuned to be very soft and the interlaying layers reduce stress and magnetostriction in the films.. Research work by Egelhoff et al showed that significantly improved softness can be achieved in laminated Conetic (Ni77Fe14Cu5Mo4) films with a total magnetic thickness of 400 nm, where the Conetic alloy has the potential to be tuned to be very soft and the interlaying layers reduce stress and magnetostriction in the films.14 These results provide a possible approach to tuning the magnetic properties of micro magnetic flux concentrators. The effect of a laminated structure on Conetic films made with sputtering deposition is investigated, and it is demonstrated that deposited laminated magnetic films can stay very soft even with the total magnetic thickness being several micrometers, and they can be suitable for application in micro magnetic flux concentrators
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