In the heated rod, electrons with spins that are aligned “up,” or with the material’s magnetic field, tend to prefer the warmer side, while those with spins pointing in the opposite direction, or “down,” tend to prefer the cooler side, the researchers report in the Oct. 9 Nature.
Engineers could harness this spin effect to design new devices for computer chips, Saitoh says. For example, a spintronic battery could produce spin imbalances at its two electrodes, and the chip could use that imbalance, instead of an ordinary electric current, and store information magnetically. Electric currents produce heat, but transferring information by flipping spins does not. Such spintronics devices would then cut down power consumption and operate at faster speeds without overheating.
The team calls the newly discovered phenomenon the spin Seebeck effect, in analogy with the thermoelectric effect discovered by physicist Thomas Johann Seebeck in the 1800s. In the thermoelectric effect, heating one side of an electrically conducting rod creates a voltage, because electrons at the warmer end become faster as they heat up and thus tend to move toward the cooler end, just like a heated gas tends to expand.