Enhanced resistance to radiation and magnetic anisotropy change by periodic pattern of dislocation networks at a W/Fe interface

A new tungsten-iron (W-Fe) interface with strong resistance to radiation damage and shear stress deformation after displacement cascades has been suggested through molecular dynamics (MD) and accelerated MD methods. Calculations of interface formation and cohesion energies indicate that semi-coherent W(100)/Fe(100) and W(110)/Fe(110) interfaces have stronger thermal stability than the incoherent W(100)/Fe(110) and W(110)/Fe(100) interfaces. The semi-coherent interfaces also strongly trap defects, resulting in a rapid decrease of the number of defects and W-Fe atomic mixing at the interface after cascades. The enhanced defect recombination and recovery is facilitated by the formation of a regular square and an irregular hexagonal dislocation network at these two semi-coherent interfaces respectively. Furthermore, it is observed for the first time that the strong resistance to shear deformation of the W(100)/Fe(100) interface before and after cascades is due to a wave-like atomic displacement induced by the square pattern, which changes the activation model of slip systems from the interface. In addition, the effect of radiation defects on the magnetic storage property of the W(100)/Fe(100) system is investigated by ab initio method. Formation of small defects and W-Fe atomic mixing decreases the magnetic storage property, as implied by the magnetic anisotropy energy (MAE) calculations. All these results indicate that even though a W(100)/Fe(100) interface exhibits good stability and mechanical property against radiation damage, a radiation protection material is needed to conserve its magnetic property for its application in magnetic memory devices in nuclear facilities and space.