Abstract

Glass-coated Cu56Ga27Mn17 magnetic microwires, resulting from thermal annealing at 523K for 1 h, have been structural and magnetically characterized. The crystalline structure shows the coexistence of four crystalline phases: a hexagonal phase with a = b = 0.4536 nm and c = 0.8386 nm lattice parameters, a cubic B2 one having a lattice parameter a = 0.29208 nm, a second fcc Cu-rich minority phase with a = 0.3592 nm, and a monoclinic CuO appearing at the sample surface. ZFC-FC-FH thermomagnetic curves performed at different applied magnetic fields in the CuGaMn microwires annealed at 523 K, show a clear coexistence of two ferromagnetic phases with a Curie temperature around 150 K for the major phase while that corresponding to the second one is above room temperature. The field effect on ZFC-FC-FH magnetization behavior displays that the increase in the applied field modifies and shifts two peaks observed in the ZFC curve, also reducing the thermal hysteresis between FC and FH curves existent in the applied field range of 50-500 Oe. The magnetization behavior exhibited by the CuGaMn annealed microwires depending on the temperature range and magnetic field value will be discussed on the basis of the coexistence of antiferromagnetic and ferromagnetic interactions. (C) 2011 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim