Evolution of the magnetic structure in TbxY1−xAg (abstract)

摘要

As nonmagnetic yttrium is substituted for terbium, TbAg changes from a conventional antiferromagnet into a complex magnetic system with components of both commensurate and incommensurate spin structures and bulk magnetic properties typical of spin‐glass behavior forx≤0.5. We have carried out neutron diffraction experiments on polycrystalline samples withx=0.15, 0.5, and 1.0 to complement our earlier studies forx=0.3.1Forx=0.5, the system orders atT≊58 K into the mixed structure observed forx=0.3, but with a much sharper (1/2 1/2 0) peak. On cooling below 40 K the incommensurate peaks almost disappear, remaining only as low‐intensity shoulders of the commensurate peak at the lowest temperature measured (T=4 K). Hysteresis is observed in the relative intensity of the two components of the structure between 45 and 55 K. Forx=0.15, the system orders atT≊18 K into the two‐component structure, but with an approximately constant intensity ratio and no evidence of hysteresis, similar to the behavior found forx=0.3. Thus, as the Tb concentration decreases, the relative stability of the commensurate and incommensurate structures appears to change. This balance between competing magnetic structures will be related to the spin‐glass properties observed in this system.