Researchers said that they found that not just the electric current, but also the thermal current flowing through magnetic tunnel structures can be monitored and controlled, simply by switching the magnetization. Such tunnel structures are often used as magnetic storage cells in MRAMs, or sensors to read data in hard disk drives. These structures consist of two magnetic layers that are separated by a 1 nm thin insulation layer. Electric current can be controlled by adjusting the resistance via the magnetic orientation of the two layers.
The scientists said that they "generated a temperature difference between the two magnetic layers" and noticed that the created electric voltage, referred to as thermoelectric voltage, also depends on the magnetic orientation of the two layers "nearly as strongly as the electric resistance." As a result, a changed magnetization also enabled them to control the thermal current flowing through the device.
If the effect can be used in a mass-produced product, future device may be able to use the energy in dissipated heat for circuit functions.