Spintronics a neologism meaning “spin transport electronics”, also known as “magneto electronics, is an emerging technology which exploits the intrinsic spin of electronics and its associated magnetic moment, in addition to its fundamental electronic charge, in solid-state devices.
The storage density of hard drives is rapidly increasing along an exponential growth curve, in part because spintronics-enabled devices like GMR (giant magnetoresistance) device and TMR (Tunnel magnetoresistance) sensors have increased the sensitivity of the read head which measures the magnetic state of small magnetic domains (bits) on the spinning platter. The doubling period for the areal density of information storage is twelve months, much shorter that Moore’s law, which observes that the number of transistors that can cheaply be incorporated in an integrated circuit doubles every two years.
MRAM, or magnetic random access memory, uses arrays of TMR or Spin torque transfer devices. MRAM is nonvolatile (unlike charge based DRAM in today’s’ computers) so information is stored even when power is turned off, potentially providing instant on computing. This MRAM has a read/write cycle of fewer than 50 nanoseconds.
Advantages of semiconductor-based spintronies applications are potentially lower power use and a smaller footprint than electrical devices used for information processing. Also, application such as semiconductor lasers using spin-polarized electrical injection has shown threshold current reduction and controllable circularly polarized coherent light output. Future applications may include a spin-based transistor having advantages over MOSFET devices such as steeper sub-threshold slope.