Effects of Ru and Ag cap layers on microstructure and magnetic properties of FePt ultrathin films

Abstract

The effects of Ru and Ag cap layers on the microstructure and magnetic properties of the FePt ultrathin films have been investigated. The results indicate that i) The Ag cap layer segregates from the FePt/Ag bilayer, lowers the FePt ordering temperature, promotes the FePt thin films to form island structure, and enhances the coercivity; ii) The Ru cap layer increases the FePt ordering temperature, helps to maintain smooth continuous structure film, and restrains the FePt (001) orientation and perpendicular magnetic anisotropy (PMA). The effects become more pronounced for the 3-nm-thick FePt thin films. The effects can be mainly attributed to the different melting point and thermal expansion stress between the cap layer and FePt thin films.

Annealing driven positive and negative exchange bias in Fe–Cu–Pt heterostructures at room temperature

“…Recently, efforts have been made to reduce the ordering temperature by introducing (a) a buffer layer [16][17][18][19][20], (b) a cap layer [21,22], and (c) addition of third element to form a ternary alloy compound [23][24][25][26]. One of the effective ways to reduce the ordering (FCC to FCT) temperature of FePt film is by adding Cu to FePt and realizing the formation of (FePt) 1-x Cu x ternary alloys (x = 0-30%) [27][28][29][30][31][32].…”

Perpendicular Magnetization Behavior of Low- Temperature Ordered FePt Films with Insertion of Ag Nanolayers

“…Even many works reported the microstructure modulation of the FePt-Ag system by the inactive atomic mobility of FePt reacted with Ag, but the corresponding evolution of the perpendicular magnetization reversal mechanism of the FePt-Ag nanocomposite structures is still deficient [ 42 , 43 , 44 , 45 , 46 ]. Due to the inactive atomic mobility of the FePt phase, the perfectly continuous film structures are usually formed at growth temperatures below 600 °C [ 47 , 48 ]. Thus, the high formation temperature is needed to achieve a granular structure of the ordered FePt with high coercivity, which is not suitable for industrial productions.…”