Giant Magneto Resistance--- Wins Physics Noble Prize for 2007

The 2007 Nobel Prize in physics has been awarded to Albert Fert and Peter Grunberg for simultaneously and independently discovering Giant magneto resistance. This property has allowed the explosion of disk-space growth and is cited as being one of the first nano-technology breakthroughs.
Magnetoresistance is the property of a material to change the value of its electrical resistance when an external magnetic field is applied to it. The effect was first discovered by William Thomson in 1856.
The magnetoresistance of conventional materials is quite small; but materials with large magnetoresistance have been synthesized now. Depending on the magnitude, it is called either as Giant magnetoresistance(GMR) or Colossal magnetoresistance(CMR). Magnetoresistance has aroused great interest recently because of possible application in devices such as read/write heads in computer discs and in sensors.
Colossal Magnetoresistance has been predominantly discovered in manganese-based perovskite oxides. This arises because of strong mutual coupling of spin, charge and lattice degrees of freedom. Hence not only high temperature superconductivity, but also new magnetoelectronic properties are increasingly discovered in materials with perovskite structures. GMR involves structures consisting of very thin layers of different magnetic materials.

The technology has allowed hard disk sensors to read and write much more data
The information is retrieved by a read-out head that scans the disk and registers the magnetic changes. The smaller and more compact the hard disk, the smaller and weaker the individual magnetic areas. More sensitive read-out heads are therefore needed when more information is crammed on to a hard disk.hard drives in computers, iPods and other digital devices. A computer hard-disk reader that uses a GMR sensor is equivalent to a jet flying at a speed of 30,000 kmph, at a height of just one metre above the ground, and yet being able to see and catalogue every single blade of grass it passes over.