Chiral nanostructured thin films can be produced through precise control of the angle of incidence of a vapor flux concurrent with substrate rotation. The technique has been employed to create unique porous iron thin film structures on Si(100) with a columnar microstructure. Scanning electron microscopy images illustrate columnar iron films produced with azimuthal rotation during sample growth with the incident flux at an angle of 75 degrees with respect to the surface normal. The columns were found to be well isolated with a narrow distribution of diameters, resulting in aspect ratios of approximately 8 to 1. Hysteresis loops reveal the columnar growth induced a large magnetic shape anisotropy relative to that observed for an iron film grown with normal incidence. The evolution of the columnar microstructure was followed from simple oblique deposition (no substrate rotation), giving a fibrous slanted microstructure, to high-speed rotation where a broad size distribution of highly faceted columnar structures was observed. The measured microstructure is related to the observed magnetic properties. (C) 1999 American Institute of Physics. [S0021-8979(99)63308-4].