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Caption : <b>fig. s1</b> sem photo [backscattered electron (bse) model] of a dta sample with nominal composition gd<sub>3</sub>ni<sub>2</sub>, after a cooling run at a rate of 20 k/min. three phases are present: primary dark crystals of equiatomic gdni (a), grey-color grains of gd<sub>3</sub>ni<sub>2</sub> (b) and light-grey crystals of gd<sub>3</sub>ni (c).

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Caption : <b>fig. s2</b> a typical dsc trace for a gd<sub>3</sub>coni specimen up to 1123 k (850°c); heating and cooling rate of 20 k/min.

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Caption : <b>fig. s3</b> distribution of neighboring atoms around gd and ni atoms in gd<sub>3</sub>ni<sub>2</sub> (a), and around gd, co and ni atoms in gd<sub>3</sub>coni (b) compounds.

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Caption : <b>fig. s4</b> magnetization and inverse magnetic susceptibility measured between 2 and 300 k and at 200 and 2000 oe for the substituted gd<sub>3</sub>co<sub>x</sub>ni<sub>2–x</sub> compounds for x = 0.5 (a), 0.75 (b), 0.85 (c), 0.95 (d).

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Caption : <b>fig. s5</b> isothermal magnetization data (at 5 k) as a function of applied magnetic field (up to 70 koe) for the substituted gd<sub>3</sub>co<sub>x</sub>ni<sub>2–x</sub> compounds for x = 0.5 (a), 0.75 (b), 0.85 (c), and 0.95 (d).

File Name : figure-s6-new.tif

Caption : <b>fig. s6</b> isothermal magnetization measured at selected temperatures around the magnetic transition for gd<sub>3</sub>co<sub>0.75</sub>ni<sub>1.25</sub> (a), and gd<sub>3</sub>co<sub>0.85</sub>ni<sub>1.15</sub> (b) compounds. arrott plots for gd<sub>3</sub>co<sub>0.75</sub>ni<sub>1.25</sub> (c) and gd<sub>3</sub>co<sub>0.85</sub>ni<sub>1.15</sub> (d). isothermal magnetic entropy change <i>vs.</i> temperature for gd<sub>3</sub>co<sub>0.75</sub>ni<sub>1.25</sub> (e) and gd<sub>3</sub>co<sub>0.85</sub>ni<sub>1.15</sub> (f) for δh = 10, 20, 30, 40, 50 koe.