Emergence of 100% Spin Polarization in Non-Collinear Magnets

Recently, large tunneling magnetoresistance (TMR) effects have been predicted and demonstrated in antiferromagnetic tunnel junctions (AFMTJs) with non-collinear antiferromagnetic (AFM) electrodes, that is promising for future information technology applications. These results indicated a very large transport spin polarization provided by AFM metals, which is unexpected due to the non-collinearity of their magnetic moments. In this work, we elucidate the origin of this giant spin polarization using simple tight-binding models and calculations based on density functional theory (DFT). Using tight-binding Hamiltonians to describe an infinite 1D chain of non-collinear magnetic moments and a 2D Kagome lattice in a non-collinear AFM phase, we show that fully spin-polarized conduction channels appear in these systems and reveal their origin. Using DFT calculations, we further demonstrate the presence of 100% spin-polarized states in non-collinear AFM antiperovskites XNMn3 (X = Ga, Sn, …) leading to giant TMR values in AFMTJs based on XNMn3 electrodes. Our results demonstrate great potential of non-collinear AFM metals for spintronics.