Magnetic properties of Fe-Cu alloys prepared by pulsed electrodeposition

Fe x Cu 100 − x metastable alloys were prepared by pulsed electrodeposition for 5 < x < 85 . The Fe-rich alloys crystallize in the bcc structure of α -Fe and the Fe-poor ones in the fcc structure of Cu. The magnetic properties of the ferromagnetic Fe-rich alloys ( x > 50 ) are reminiscent of those observed in Fe-Cu alloys prepared by other methods. The Curie temperature decreases regularly with decreasing x. In the Fe-poor alloys ( x ≤ 30 ) , the observed properties indicate that Fe-rich clusters form within a Cu-rich matrix. In the x = 10 alloy, the Fe clusters are found to be superparamagnetic at room temperature, but a superferromagnetic order develops below a critical temperature of about 120 K. It is suggested that the intercluster coupling is mediated by Ruderman-Kittel-Kasuya-Yosida interactions which are predominantly positive due to the very short intercluster distances.