Planar Hall effect sensors - effects of shape and size

Our work concerns permalloy. This compound is one of the most widely used magnetic materials. The fact that it has large magnetotransport effects made it one of the leading candidates for various applications. One of these applications concerns the ability to measure magnetic fields via its resistivity anisotropy. A recent paper of our group explores the effects of shape and size on properties of elliptical magnetic sensors based on the Planar Hall effect. The paper presents measurements of thin-film permalloy sensors in the form of ellipses having different aspect ratios along with extensive numerical simulations. We identify upper limits above which hysteresis effects intensify, and lower limits below which the remanent state is unstable, and address the role of the ratio between the sensor thickness to its other dimensions. This work may form the basis for designing more sensitive planar Hall effect magnetic sensors.  

           A permalloy ellipse on Si substrate            A sensor with current and voltage leads made of gold