Technology

Advanced
Magnetic
Sensing
Performance

Crocus Technology has developed and patented its advanced XtremeSense TMR technology (Tunnel Magneto-Resistance) to provide superior magnetic sensing performance for use in many applications. The advanced XtremeSense TMR technology enables high magnetic sensitivity, stable performance over temperature, low noise and low power consumption which allows it to be used in a broad spectrum of applications. TMR sensors can replace many Hall Effect sensors with increased performance and cost savings.

TMR is based on different physics phenomena. The magneto-resistance effect is the property of a device to change its electrical resistance value under the influence of an external magnetic field, therefore allowing enhanced electrical detection of magnetic fields in various applications.

Comparison of Magnoresistive Technology

Magnetic
Tunnel
Junction and
Quantum
Physics

At the heart of the advanced XtremeSense TMR technology, is a thin-film magnetoresistive device, the so-called Magnetic Tunnel Junction (MTJ). In its simplest form the MTJ consists of two electric-conducting magnetic layers on either side of a thin (nanometer-scale) but highly robust insulating layer. One magnetic layer has a fixed magnetic moment direction, while the other can change freely to follow the direction of the local magnetic field.

According to classic physics, despite how thin the insulating layer is, it should prevent any current flow between the two magnetic layers. However, in this nano-world, quantum physics allows electrons to “tunnel” across the atoms of the thin insulating material with a resistance that depends on the sensitivity of the relative orientation of the two magnetic layers. Therefore, as the Free Layer magnetization follows the direction and intensity of the ambient magnetic field, its magnetic orientation is modified with respect to the Reference Layer. This change in relative magnetic orientation will significantly change the probability of quantum tunneling between the two layers and therefore the electron flow through the device.

Two clear states
can be defined

1 The parallel state: The Free Layer magnetization direction is pointing in the same direction as the Reference Layer’s magnetization, this state allows current the flow through the MTJ.
2 The anti-parallel state: the Free Layer magnetization direction is pointing opposite the Reference Layer’s magnetization; this state greatly limits the current flow through the MTJ. Between the two states lies a substantially linear region that on XtremeSense TMR MTJs is optimized in CrocusTechnology’s linear products.

Electrical Current Flow

Making TMR Possible

This variation in electrical resistance is then immediately detected and amplified to accurately sense the local magnetic field.

This feature, which is based on quantum physics, creates the TMR advanced sensor with higher sensitivity, lower power consumption, and more stable characteristics

XtremeSense® TMR

XtremeSense® TMR provides the highest sensitivity, the lowest power consumption, and smallest size by comparison to the other magnetic technologies such as Hall, AMR, and GMR.

These sensors have excellent working dynamic range, with high linearity, low hysteresis, and high sensitivity characteristics (i.e., a large magneto-resistive response curve slope).

Our R&D Center

Grenoble, France

Developer and Manufacturer of TMR Sensor Technology

  • Technology, process development and pre-production
  • Magnetic simulation and design
  • TMR sensor design
  • TMR materials development
  • TMR sensor deposition
  • TMR sensor characterization
  • TMR sensor testing at wafer level and package level
  • Advanced simulation & modeling

For more information about performance advantage of TMR over other magnetic sensing technologies, please read the application note AN117.

Hall vs. TMR

TMR sensors more accurately measure the full dynamic range and provides a cleaner signal.