With the advancement in material science and quantum mechanics, a newer technology is now being adapted into magnetic switches that takes advantage of electron tunneling that can occur between magnetic structures which are separated by an ultra-thin dielectric layer.

The top and bottom blocks shown in Figure 1-10are actually a complex layering of conductive magnetic materials which are able to produce the TMR effect. During fabrication, the bottom layer has had a specific magnetization applied and is commonly referred to as the pinned layer. Also, the top layer is considered to be free.

When an applied magnetic field is introduced to the structure the overall resistance of the material can vary based on the relative direction of the field. When the applied magnetic vector is parallel to the magnetization of the substrate layer, then the relative impedance can be at the maximum, but as the applied field approaches the anti-parallel direction to the flow of current, then the impedance can drop to a minimum shown in Figure 1-11.

As a result of the normal fabrication processes for this technology, TMR sensors are typically constructed so that the sensors are sensitive to the field applied within the XY plane.