Current-driven excitations in magnetic multilayer nanopillars from 4.2 K to 300 K

We report direct experimental evidence of an energy threshold for spin-transfer-induced magnetic excitations in Co/Cu/Co nanopillars from temperature dependent measurements of current-induced excitations. The current threshold of excitations decreases when the temperature is increased from 4.2 to 300 K. However, the product of the current threshold and the pillar resistance stays almost temperature independent up to a temperature of ∼150K. This behavior supports the energy-threshold mechanism for spin-transfer-induced magnetic excitations. © 2004 The American Physical Society.