Abstract
Three ferromagnetic pyrochlore systems were studied to investigate the role of the ionic size versus moment on the magnetic properties of the sublattice. The Curie temperature for and Lu remained nearly constant for but the magnetization data show characteristics of spin-glass behavior in low magnetic fields, and at 5 T, the magnetization fails to reach the expected found by 0.5 T in and . A frustrated, minor antiferromagnetic component apparently competes with the ferromagnetic component of the interactions to give a minor antiferromagnetic component to the major ferromagnetic spin alignment of the ions. A for and Yb remains nearly constant in the system and increases systematically from 19 to 42 K with Dy concentration in , which clearly shows that a ferromagnetic interaction between the -ion and -ion spins favors ferromagnetic alignment of the -ion spins to double the magnitude of by relieving the frustration of the sublattice. The -ion size has little effect as the Mn-O-Mn bond angle changes by no more than with changing ionic radius of the ion.
- Received 13 July 2010
DOI:https://doi.org/10.1103/PhysRevB.82.132407
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