The crystal and magnetic structures of Cr,Fe,-,VO,-l solid solutions with x=0.25, 0.50, and 0.75 have been investigated by neutron diffraction and magnetic susceptibility measurements. Site occupancy refinements and geometrical arguments show that there is a small degree of Cr3+/Fe3+ ordering between two inequivalent octahedral sites with increasing x, as Cr3+ preferentially occupies the site that can become more regular. Antiferromagnetic order is observed below the N6el temperature TN=21.8(5) and 17.9(2) K for the x=O.25 and 0.50 samples, respectively, and can be described by the propagation vector (0, z,, 5) where z,=O.161(3) for x= 0.25 and z, = 0.25(1) for x= 0.50. The magnetic structures contain clusters of four antiferromagnetically coupled spins, but the order between clusters is frustrated, resulting in magnetic spirals that propagate along the monoclinic b axis. The frustration also gives rise to increasing amounts of short-range magnetic order with increasing x, such that no long-range order is observed for x=O.75.

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We report a simple and nondestructive method to determine directly the spatial profiles of the constituent elements in a synthetic multilayered material with a resolution of 10–20 Å. This has been accomplished by measuring the x-ray diffraction Bragg peak intensities over a large range of energies, and interpreting these data using a dynamical theory to deduce the first few Fourier coefficients of the relevant spatial profiles. We present initial results for Ti-Si multilayer samples grown by thermal deposition. These results demonstrate extensive interdiffusion of the silicon into the titanium layers, even without annealing.