Anisotropic magnetotransport measurements are reported on ${\mathrm{Fe}}_{1∕4}\mathrm{Ta}{\mathrm{S}}_2$ single crystals grown by vapor transport. Both the magnetization and resistivity are extremely anisotropic, with the magnetic moments aligned parallel to the $c$ crystallographic direction. ${\mathrm{Fe}}_{1∕4}\mathrm{Ta}{\mathrm{S}}_2$ orders ferromagnetically below $T_C=160\mathrm{K}$ and displays very sharp hysteresis loops in the ordered state for $H\Vert c$. The corresponding magnetoresistance is negative, and it qualitatively reproduces the features observed in the $M\left(H\right)$ data by showing a sharp drop around the critical field $H_s$ for the moment reversal. The magnetization switching time shows an unusual increase with increasing temperature. For field applied within the $ab$ plane, the magnetization remains small and linear in field up to $5\mathrm{T}$, and the magnetoresistance is positive and quadratic in field, with no visible hysteresis. The squareness of the $H\Vert c$ $M\left(H\right)$ loops and the high critical field for the magnetization switch ($H_s=3.7\mathrm{T}$ at $T=2\mathrm{K}$) allow us to classify ${\mathrm{Fe}}_{1∕4}\mathrm{Ta}{\mathrm{S}}_2$ as a strong ferromagnet.

• Received 20 October 2006

DOI:https://doi.org/10.1103/PhysRevB.75.104401