Magnetic tunnel junctions (MTJs) have played a central role in spintronic devices, and researchers are working to improve their performance. A prominent achievement that accelerated the technology’s practical applications was the realization of giant tunnel magnetoresistance (TMR) ratios by using rock-salt type MgO crystalline barrier. Researchers have now succeeded in applying MgGa2O4 to a tunnel barrier, the core part of an MTJ, as an alternative material to more conventional insulators.