SPIN HOLOGRAPHY

The interference of the directly emitted photoelectron wave and the wa ve scattered coherently by neighboring atoms gives holographic fringes in the photoelectron emission intensity I((R) over cap). In the elect ron-emission holography technique in surface physics, I((R) over cap) is inverted holographically to give a three-dimensional image of the e nvironment of the source atom. Earlier [E. M. E. Timmermans, G. T. Tra mmell, and J. P. Hannon, Phys. Rev. Lett. 72, 832 (1994); J. Appl. Phy s. 73, 6138 (1993)], we pointed out that the polarization pattern P((R ) over cap) similarly can be viewed as a hologram of the spin environm ent of the source atom by virtue of the exchange scattering of the pho toelectron by the neighboring atoms. In this paper, we point out that spin-orbit correlations in the photoelectron initial state are respons ible for holographic spin-dependent contributions to the intensity hol ogram I((R) over cap), even if the directly emitted photoelectrons are unpolarized. This remarkable result implies that the emission intensi ty contains spin information just as the polarization pattern P((R) ov er cap). Although the spin-dependent signal in the hologram is rather small (similar to 5% in most cases of interest), we show how spin info rmation can be extracted from the intensity hologram, making use of th e point symmetry of the environment of the source atom. This way of an alyzing photoelectron intensity holograms to extract short-range spin information opens up a new avenue for surface magnetism studies.