Colossal magnetoresistance in La2-2xSr1+2xMn2O7 single crystals

We performed magnetisation (M) and transport measurements along the ab plan e and the c direction in La2-2xSr1+2xMn2O7 single crystals for x = 0.4. In addition to a sharp para-ferromagnetic transition at T-c = 125 K, a weak ma ximum in M was found around 265 K. A sharp drop of resistivity at T-c assoc iated with a semi-conductor to metal transition was found for both current orientations. The colossal magnetoresistance of the compound CMR = - (rho(H ) - rho(0))/rho(0) was found to be similar to 100% in a held of 8 T near T- c. In contrast with the well-known La1-xSrxMnO3 type manganites, a CMR effe ct larger than 10% was present at all temperatures ranging between 5 and 30 0 K. (C) 1999 Elsevier Science B.V. All rights reserved.