  We examine spin dependent transport in a quantum interferometer composed of
magnetic atomic sites based on transfer matrix formalism. The interferometer,
threaded by a magnetic flux $\phi$, is symmetrically attached to two
semi-infinite one-dimensional (1D) non-magnetic electrodes, namely, source and
drain. A simple tight-binding model is used to describe the bridge system, and,
here we address numerically the conductance-energy and current-voltage
characteristics as functions of the interferometer-to-electrode coupling
strength, magnetic flux and the orientation of local the magnetic moments
associated with each atomic site. Quite interestingly it is observed that, for
$\phi=\phi_0/2$ ($\phi_0=ch/e$, the elementary flux-quantum) a logical XOR gate
like response is observed, depending on the orientation of the local magnetic
moments associated with the magnetic atoms in the upper and lower arms of the
interferometer, and it can be changed by an externally applied gate magnetic
field. This aspect may be utilized in designing a spin based electronic logic
gate.
