  The objective of this paper is to draw attention to a possible new approach
for measuring the spin excitation spectrum of a spin array by placing it in
intimate contact with the channel of a spin-valve device in an anti-parallel
(AP) configuration. We show, using realistic device parameters, that the second
derivative of the current $\partial^2I/\partial V^2$ should exhibit peaks whose
location corresponds to the energy of excitation and whose height is its
strength. The effect is maximum for ideal half metallic contacts in AP
configuration but we show that even with contacts that are less than ideal, the
spin signals can be extracted using a de-embedding scheme. Compared to existing
techniques our proposal has three attractive features: (a) high sensitivity
down to single spins, (b) high spatial resolution limited only by the
wavefunctions of the individual spins and (c) a relatively common device
structure to which a lot of current research is devoted
