Abstract
We report comprehensive studies of the crystallographic, magnetic, and thermal properties of a spinel-type magnetically frustrated compound, , and a magnetically diluted system, . These studies revealed the effects of dilution and disorder when the tetrahedral magnetic Co ion was replaced by the nonmagnetic Zn ion. Low-temperature anomalies were observed in magnetic susceptibility at . A multicritical point was apparent at and , where the antiferromagnetic, spin-glass-like, and paramagnetic phases met. At that point, the quenched ferromagnetic component induced by a magnetic field during cooling was sharply enhanced and was observable below . At , magnetic susceptibility and specific heat were described by temperature power laws, , in accord with the site percolation threshold of the diamond lattice. This behavior is reminiscent of a quantum critical singularity. We propose an -temperature phase diagram in the range for . The transition temperature of determined from magnetic susceptibility measured under hydrostatic pressure increased with increasing pressure.
5 More- Received 26 December 2014
- Revised 21 May 2015
DOI:https://doi.org/10.1103/PhysRevB.91.224412
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