TMR sensor is an epoch-making magnetoresistance effect sensor which has been applied to industrial application in recent years. TMR sensor has a much higher resistance change rate compared to AMR and GMR sensor, thus obtained many merits include low cost and power consumption, high response frequency and sensitivity. SDM has also collected some experience in TMR sensor magnet because of the widely use of TMR sensor.
What is Tunneling Magnetoresistance Effect?
The sandwich structure made by two ferromagnetic layers and insulating layer can be called magnetic tunnel junctions (MTJs). Tunneling magnetoresistance of MTJs will be changed when changing the relative orientation of two ferromagnetic layer’s magnetic moment, and this phenomenon is known as tunneling magetoresistance (TMR) effect. The structure of TMR and GMR component is basically the same, and current direction of TMR and GMR component is perpendicular and parallel to the layer respectively.
The magnetization direction of the pinned layer is fixed, and magnetization direction of the free layer can be adjusted according to the external magnetic field, therefore, electric resistance of TMR component will also changes. TMR component shows the least resistance once magnetization direction of the free layer is parallel to the pinned layer’s and then high-current flow through the barrier. Instead, resistance will significantly increase when magnetization direction antiparallel, thus little current flow through the barrier.
From the angle of quantum mechanics, when magnetization directions of two ferromagnetic layers are parallel to each other, electrons of majority-spin and minority-spin subband enters into unoccupied states of another ferromagnetic layer’s majority-spin and minority-spin subband respectively, then tunnel current is relatively high and component is in the low resistance state. When magnetization directions are antiparallel to each other, the opposite occurs. The electrons of majority-spin and minority-spin subband enter into unoccupied states of another ferromagnetic layer’s minority-spin and majority-spin subband respectively, then tunnel current is relatively low and component is in the high resistance state.
About TMR Sensor Magnet
SDM team will help customers to choose suitable TMR sensor according to the detailed technical specifications, and looking forward to cooperating with relevant customers.
