FROZEN SPIN-WAVE STRUCTURE ON THE NIO(100) SURFACE OBSERVED BY METASTABLE HE 2(3)S SCATTERING

Elastic scattering of metastable 2(3)S He has been used for the first time to determine the long-range spin ordering on the surface of an an tiferromagnetic insulator. The diffraction pattern obtained from a NiO (100) surface is interpreted as a frozen spin-wave structure in the [1 0] direction with a period of 6xa. The diffraction arises from a spati al variation of the beam attenuation due to scattering from the period ic local spin ordering on the surface and is not caused by a spin-spin interaction. The results have been modeled with a modified version of the eikonal approximation using a dissipative, hard, corrugated wall.