The magnetically-sensitive transistor (also known as the spin transistor or spintronic transistor--named for spintronics, the technology which this development spawned), originally developed in the 1990's and currently still being developed, is an improved design on the common transistor invented in the 1940's. The spin transistor comes about as a result of research on the ability of electrons (and other fermions) to naturally exhibit one of two (and only two) states of spin: known as "spin up" and "spin down". Unlike its namesake predecessor, which operates on an electric current, spin transistors operate on electrons on a more fundamental level; it is essentially the application of electrons set in particular states of spin to store information.

One advantage over regular transistors is that these spin states can be detected and altered without necessarily requring the application of an electric current. This allows for detection hardware (such as hard drive heads) that are much smaller but even more sensitive than today's devices, which are forced to rely on noisy amplifiers to detect the minute charges used on today's mass storage devices. The potential end result is devices that can store more in less space and consume less power, using less costly materials. The increased sensitivity of spin transistors is also being researched in creating more sensitive automotive sensors, a move being encouraged by a push for more environmentally-friendly vehicles.

A second advantage of a spin transistor is that the spin of an electron is semi-permanent and can be used as means of creating cost-effective non-volatile solid-state storage that does not require the constant application of current to sustain. It is one of the technologies being explored for Magnetic Random Access Memory (MRAM).

Because of its high potential for practical use in the computer world, spin transistors are currently being researched in various firms throughout the world, such as in England and in Sweden. Recent breakthroughs have allowed the production of spin transistors, using readily-available substances, that can operate at room temperature: a precursor to commercial viability.