Tuning Damping And Magnetic Anisotropy In Ultrathin Boron-Engineered Mgo/Co-Fe-B/Mgo Heterostructures

Nanometer-thick Co-Fe-B/MgO based structures have been widely accepted as the preferred system for immediate and long-term goals in magnetic random access memory (MRAM) devices because of excellent spin-torque efficiency and promise for high-density MRAM. To realize next-generation ultra-low-power MRAM, further lowering of power consumption in these structures is a crucial ongoing effort. Gilbert damping is one critical material parameter toward lowering energy consumption but is traditionally large (approximate to 10(-2)) in these Co-Fe-B/MgO systems. Here, Gilbert damping of (1.3 +/- 0.3) x 10(-3) from a perpendicular double Co-Fe-B/MgO interface system engineered at different boron compositions is reported. Remarkably, this value is achieved with approximate to 1 nm of Co-Fe-B thickness while maintaining magnetic anisotropy of 0.4 Merg cc(-1). An unusual damping trend that scales with layer thickness in high-boron content films established from both experiments and first-principles calculations is reported.