Large magnetoresistance and magnetocaloric effect above 70 K in Gd 2 Co 2 Al , Gd 2 Co 2 Ga , and Gd 7 Rh 3

The electrical resistivity, magnetization, and heat-capacity behavior of the Gd-based compounds, ${\mathrm{Gd}}_{2}{\mathrm{Co}}_{2}\mathrm{Al}$, ${\mathrm{Gd}}_{2}{\mathrm{Co}}_{2}\mathrm{Ga}$, and ${\mathrm{Gd}}_{7}{\mathrm{Rh}}_{3}$, ordering magnetically at ${T}_{C}=78\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, ${T}_{C}=76\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, and ${T}_{N}=140\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, have been investigated as a function of temperature and magnetic field. All these compounds are found to show large magnetoresistance (with a negative sign) in the paramagnetic state at rather high temperatures with the magnitude peaking at respective magnetic ordering temperatures. There is a corresponding behavior in the magnetocaloric effect as inferred from the entropy derived from these data.