Three-Dimensional Non-Volatile Magnetic Universal Logic Gates

We present an experimental study on ultra-dense 3-D non-volatile magnetic universal logic gates with reconfigurable AND and OR functions. A four-layer magnetic structure with a net thickness of less than 30 nm is employed as a study illustration of a highly scalable magnetic logic device. In the device, the magnetic state of the top output "soft" layer depends on the magnetic states of the remaining three "hard" layers used as two input and one reset layers, respectively. To build vertically oriented magnetic devices with a gradient of the coercivity and the magnetization across the thickness, we use Co/Pd multilayers sputter-deposited via a combinatorial synthesis. Through a focused magneto-optical Kerr effect (F-MOKE) study, we relate input and output states in the 4-layer logic device to shoulders on major and minor M-H hysteresis loops. We use magnetic force microscopy (MFM) to identify magnetic logic operations.