As transistors approach atomic dimensions, miniaturization becomes more problematic. One possible solution to this barrier is to use electron spin controlled conduction in magnetic semiconductor devices.

Researchers led by Bruce Wessels, Northwestern University, USA, have created a bipolar magnetic junction transistor that shows amplification and operation at room temperature. Thin films of an Indium-Manganese-Arsenic alloy were shown to amplify the magnetic field due to the magnetoresistance of the InMnAs heterojunction.

This marks the first occasion that control of electron spin and amplification of signals is seen at room temperature. Potential applications for the device include magnetic sensors such as MRIs, and the device could be used in new computer logic architectures where the spin of the carriers is utilized.

• Magnetoamplification in a Bipolar Magnetic Junction Transistor
  N. Rangaraju, J. A. Peters, B. W. Wessels,
  Phys. Rev. Lett. 2010, 105, 117202.
  DOI: 10.1103/PhysRevLett.105.117202