Phase separation and magnetic properties of Nd60Fe30Al10 thin films

Abstract

In this letter we report results of the investigation of Nd60Fe30Al10 thin films prepared by electron-beam evaporation and studied by analytical transmission electron microscopy, x-ray diffraction, and magnetometry. Structural and magnetic characterizations show the existence of an amorphous matrix, which embeds a second glassy phase. The observed microstructure confirms the tendency of the Nd60Fe30Al10 system to show phase separation and to form an intrinsic composite as previously reported for slow-cooled bulk samples of the same composition. The magnetic properties of the thin films prepared with high cooling rate are discussed, taking into account magnetic pinning effects of the main magnetic phase.

Rare earth based bulk metallic glasses

“…Schneider et al attributed the intrinsic composite structure to a phase separation process taking place in the melt or the supercooled liquid state [55][56][57]. Sun et al shown the existence of two amorphous magnetic phases in melt-spun Nd 60Àx Y x Fe 30 Al 10 (x = 0, 10, 30) ribbons [66,67].…”

“…Besides the paramagnetic phases, the grains boundaries, surfaces and magnetic inhomogeneities can play an important role as pinning sites of domain walls. The strong domain wall pinning mechanism (the pinning criterion is satisfied when: a » d 2 , where a is the lateral area of a single pin and d is the wall width [65]) has been proved in these Nd-based alloys from the temperature dependence of coercivity [55][56][57][58][59][60]69]. This is because that the condition of large impediments and narrow domain walls (small d) are easily favored by the inhomogeneous structure and the large RMA in the Ndbased alloys.…”

“…The hard magnetism doesn't change significantly with annealing around T g but usually disappear when the samples are completely crystallized [9,13]. Although it is generally accepted that the large coercivity is attributed to a variety of different metastable phases (or clusters) and microstructure, the interplay between the local structures and magnetism remains controversial [9][10][11][12][13][55][56][57][58][59][60].…”

“…Nano scale clusters consisting of Nd and/or transitional metals are generally observed by high resolution transmission electron microscopy, Mössbauer spectra measurements, magnetic and resistance measurements, and isothermal calorimetry investigation, etc., in Nd-and Pr-based glasses [9][10][11][12][13][55][56][57][58][59][60][61][62][63][64][65]. Schneider et al attributed the intrinsic composite structure to a phase separation process taking place in the melt or the supercooled liquid state [55][56][57].…”

Origin of perpendicular magnetic anisotropy and evolution of magnetic domain structure of amorphous Pr–TM–B (TM=Fe, Co) films

“…RE-TM films are required to have a single amorphous phase for their practical application [10]. It is known that the preparation of the single amorphous phase Nd-Fe film with high RE content is difficult because of phase separation induced by the positive mixing heat of Nd and Fe [11,12]. Therefore, in a previous study, an amorphous Pr(Fe,Co) film with low RE content was selected as the subject of research.…”