Researchers from the University of Cambridge in the UK have developed the world's first 3D microchip, based on Spintronics technology. The chip basically uses atoms to store and transfer the data - and not electronic transistors. This may lead to 3D MRAM chips that have a large memory density - thousands of times larger than what's available today.
To create this chip they used sputtering - effectively making a sandwich on a silicon chip of cobalt, platinum and ruthenium atoms. The cobalt and platinum atoms store the digital information in a similar way to how a hard disk drive stores data. The ruthenium atoms act as messengers, communicating that information between neighboring layers of cobalt and platinum. Each of the layers is only a few atoms thick.
Using MOKE (a laser-based technique) the chip was probed at different layers and saw they could see the data 'traveling' from the bottom of the chip to the top. These results were confirmed with another, different measurement method.