  We introduce the technique of Entangled-Beam Reflectometry for extracting
spatially correlated (magnetic or non-magnetic) information from material
surfaces or thin films. Our amplitude- and phase-sensitive technique exploits
the coherent nature of an incoming entangled probe beam, of matter or light
waves, undergoing reflection from the surface. Such reflection encodes the
surface spatial structure into the probe's geometric and phase-derived
Goos-H\"anchen shifts, which can then be measured to unveil the structure. We
investigate the way these shifts depend on the wave packet widths, and
illustrate our technique in the case of in-plane periodic (non-)magnetic
structures by utilizing spin-path mode-entangled neutron beams.
