Zothecula writes "A major obstruction to the development of practical 3D microchips is moving data and logic signals from one layer of circuitry to another. This can be done with conventional circuitry, but is quite cumbersome and generates a good deal of heat inside the 3D circuit. Physicists at the University of Cambridge have now developed a spintronic shift register that allows information to be passed between different layers of a 3D microchip. 'To create the microchip, the researchers used an experimental technique called ‘sputtering’. They effectively made a club-sandwich on a silicon chip of cobalt, platinum and ruthenium atoms (abstract). 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 neighbouring layers of cobalt and platinum. Each of the layers is only a few atoms thick. They then used a laser technique called MOKE to probe the data content of the different layers. As they switched a magnetic field on and off they saw in the MOKE signal the data climbing layer by layer from the bottom of the chip to the top.'"