Magnetic Tunnel Structure (image) Physikalisch-Technische Bundesanstalt (PTB) Caption A magnetic tunnel structure consists of two magnetic layers (red and blue) separated only by a thin insulation layer of approx. 1 nm (grey) - the so-called "tunnel barrier". If a temperature difference T is generated via the barrier, then the thermoelectric voltage VTh drops between the hot (red) layer and the cold (blue) layer. If the magnetic orientation, e.g. of the hot layer compared to that of the cold layer (arrows), is changed, this leads to a strong change in the measured thermoelectric voltage. Credit Image courtesy of Schumacher/PTB Usage Restrictions None Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.