High coercivity of ultra-high-density ordered Co nanorod arrays

Abstract We report on magnetic properties of well-ordered ultra-high density (1.25×10 12 /in 2 ) arrays of vertically oriented high-aspect-ratio Co nanorods having a 14 nm diameter. The arrays were fabricated by electrodeposition within the pores of a nanoscale template derived from films of diblock copolymers. We find large coercivity enhancement ( H c ≈3 kOe at 5 K and 800 Oe at 300 K) relative to a continuous Co film of comparable thickness. The high coercivity in our ordered arrays is contrasted with a distinct decrease of coercivity below ∼50 nm rod diameter in a randomly positioned nanorod assembly.