Peltier effect in metallic junctions with CPP structure

The bottom shift in a parabolic baseline of resistance-current (R--I) curves in trilayer current perpendicular to plane-giant magnetoresistance (CPP-GMR) elements is often observed in current induced magnetization reversal (CIMR) experiments. We fabricated CPP-metallic junction elements with various metal combinations (Co/Au, Cr/Au, Cr/Co, Cr/Cr), and measured the R-I curves. Our results reveal that the direction of the shift is coincident with the sign of the Peltier coefficient of the CPP structure, and the amount of the shift is proportional to the Peltier coefficient. We estimated the Peltier coefficients by using the current where the Joule heating and the Peltier cooling compensates, and found that the Peltier coefficients are larger than those obtained from bulk materials. The expected cooling power of the CPP-Co/Cr elements was about 100 μW, which results in relatively large areal cooling power (∼10⁵ W/cm²) because of the large current density (∼10⁷ A/cm²).