The magnetic properties and microstructures of Fe-Cr-Co thin films obtained by ion beam sputtering

Fe-Cr-Co ternary alloy films were obtained by ion beam sputtering. According to their chemical composition, the specimens can be classified into two groups: (1) Fe-XCr-Co (X= 28, 40, 50, 60, 70 wt.%), WFe/WCo = 1; (2) Fe-28Cr-XCo (X = 15, 25,36, 45, 56 wt.%). After sputtering, the films were heat-treated at temperatures within the miscibility gap. After annealing, the separated phases and lattice images were determined by high resolution analytical electron microscope. With an increase in the Cr content, both the Ms and Mr values decrease while Hc tends to increase. For the Fe-XCr-Co alloys, a typical Hc value of 783 Oe for the Fe-60Cr-20Co film was obtained after aging at 550 °C for 80 min. However, the Fe-Cr-XCo alloys have higher Ms, Mr values, loop squareness and smaller Hc values compared with Fe-XCr-Co alloys. The maximum Ms, Mr values and loop squareness for the Fe-28Cr-15Co alloy are 1555 emu cm−3, 1265 emu cm−3 and 0.813 respectively. Raising the Co content can increase Hc. As a whole, the heat-treatment time for the Fe-Cr-Co thin films is much less than that ʹof bulk materials.