GMR (Giant magneto-Resistance) Essay Example | Topics and Well Written Essays - 2250 words

GMR (Giant magneto-Resistance) - Essay Example The path thus travelled is called the mean free path length. The electrical resistance is directly proportional to this mean free length. The inference is, more the free length less is the bombardment of the electron with other atomic particles hence less is the resistance of the material. However in materials that are very thin the chances of electrons reaching its outer boundary very quickly and getting dispersed are more than getting scattered by other electrons within the material itself. The low thickness of the material thus creates it difficult for the electrons to travel thereby increasing the resistance. The diagram indicated above show the manner in which resistivity increases with decrease of mean free path. In order to achieve this GMR effect another key in the construction of this film is that these are manufactured in thin layers of magnetic and non-magnetic materials.( Application Notes for GMR Sensors, 2010) The GMR film is such that the magnetization of the two layers separated by the non magnetic layer creates an anti-ferromagnetic coupling. It means when there is no externally applied magnetic field the magnetization of these two layers is in the opposite direction. Under the influence of an external magnetic field the electrons in each magnetic layer aligns according to its spin. Since the spin direction is opposite in these two layers either electron from each layer scatters off the boundary of the other magnetic layer. This results in a huge decrease of the mean free length of the electron causing an increase in electrical resistance. If however the magnetic field exceeds a certain limit this boundary barrier is overcome as all electrons in both the magnetic layers acquire the same spin. Thus the movement of electrons are eased leading to decrease in resistance.( Application Notes for GMR Sensors, 2010) The