Effect of subsidiary phase on the magnetic and transport properties of Sr1.6La1.4Mn2O7

Temperature and field dependent magnetic and transport measurements on a po lycrystalline sample of Sr1.6La1.4Mn2O7 reveal distinct magnetic peaks abov e the ferromagnetic ordering temperature T-C approximate to 90 K. The magne tic moment of the subsidiary phases identified as perovskitic impurities by a relation between the Volume fraction and the corresponding magnetic mome nt does not couple with that of Sr1.6La1.4Mn2O7 in the high temperature ran ge. This is evidenced by the presence of two slopes, dM/dH, in the M(H) cur ves and two different field dependences, H and H-2, in the rho (H) curves. On the other hand, a simple slope, dM/dH, in the low temperature regime hin ts at an exchange coupling between the magnetic moments of the two phases.