The Co(Cr) and Cr(Co) solid-solution nanocapsules have been fabricated by arc discharge in atmosphere of argon and hydrogen. The structure and composition of the nanocapsules of two types are investigated by means of x-ray diffraction, high-resolution transmission electron microscope, and energy dispersive spectroscopy analysis. The Cr(Co) and Co(Cr) nanocapsules show shell/core structure with different shape characteristics. The magnetic properties of the Co(Cr) and Cr(Co) nanocapsules are studied. The blocking temperatures of the Co(Cr) and Cr(Co) nanocapsules are determined to be 96 and 14K, respectively. The magnetization of Cr(Co) nanocapsules is contributed by the uncompensated moments in bcc chromium lattice and small cobalt particles.

In this letter, we report on measurements of current-induced magnetization switching (CIMS) in current-perpendicular-to-plane exchange-biased spin-valves (ESPVs). The structures of the ESPVs are all “antisymmetric,” but with different thickness of a ruthenium (Ru) layer. It is confirmed that the “antisymmetric” structures largely enhance the spin transfer effect and therefore reduce critical current densities for the CIMS. The effect of the Ru layer on the spin transfer in the ESPVs is also systematically studied. With a decrease of the Ru layer’s thickness, the critical current densities can be further reduced. The lowest critical current we achieved in an “antisymmetric” structure is 1×106A∕cm2, which realizes a reduction of more than one order of magnitude compared with all the reported works.