Sharp switching of the magnetization in Fe$_{1/4}$TaS$_{2}$

Anisotropic magneto-transport measurements are reported on Fe$_{1/4}$TaS$_{2}$ 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. Fe$_{1/4}$TaS$_{2}$ orders ferromagnetically below T$_{C}$ = 160 K and displays very sharp hysteresis loops in the ordered state for H$\vert \vert $c. The corresponding magnetoresistance is negative, and it qualitatively reproduces the features observed in the M(H) data, by showing a sharp drop around the critical field H$_{s}$ for the moment reversal. For field applied within the ab plane, the magnetization remains small and linear in field up to 5 T, and the magnetoresistance is positive and quadratic in field, with no visible hysteresis. The squareness of the H$\vert \vert $c M(H) loops and the high critical field for the magnetization switch (H$_{s }$= 3.7 T at T = 2 K) allow us to classify Fe$_{1/4}$TaS$_{2}$ as a strong ferromagnet.