Crystal Grid (IMAGE) Johannes Gutenberg Universitaet Mainz Caption This is a diagram illustrating spin-up (red) and spin-down (blue) electrons in a crystal grid. Credit Ill.: Condensed Matter Theory Group, JGU Usage Restrictions This image may only be used in connection with the press release "Giant magnetoresistance systems examined by means of ultrafast terahertz spectroscopy", issued by Johannes Gutenberg University Mainz on July 7, 2015. License Licensed content 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.