Influence of magnetization on the reordering of nanostructured ball-milled Fe-40 at. % Al powders

Disorder effect on the magnetic behavior of mechanically alloyedFe1−xAlx(0.2Zamora1, Alcázar2, Vélez3 et al. 2009Phys. Rev. B482220View full textAdd to dashboardCite

“…The existence of disorder is evidenced by the Mössbauer data and also supported by previously reported results on this type of alloys which indicate that ͑i͒ MA produces disordered alloys and ͑ii͒ the disorder increases with t. 11,[17][18][19][20][21][22]32 We assume that the competitive interactions, which were reported in previous papers for ordered and disordered melted samples and MA samples, are due to the F interaction between nearest-neighbor ͑nn͒ Fe atoms and the AF nextnearest-neighbor interaction ͑nnn͒ between Fe atoms. The disordered character of the sample allows us to consider the presence of different types of Fe sites: ͑i͒ sites very rich in nn Fe atoms ͑8 or 7͒; ͑ii͒ sites with a majority or intermediate number of nn Fe atoms ͑6, 5, or 4͒ which, in accordance with the composition of the sample ͑40 at.…”

“…The results suggest that the milling time stabilizes the ferromagnetic order of the sample and this fact is associated to the increase in the disorder in the system. The increase in disorder with increasing milling time in the mechanically alloyed Fe-Al system has been observed by different authors 11,[17][18][19][20][21][22]32 and in our case is evidenced by the fact that the peaks corresponding to the different more probable local configurations around the Fe sites progressively disappear with the increasing milling time and the HMFD shows just one maximum and a symmetric shape around the most probable Fe site for t =36 h. Figure 6 shows the evolution of ͗B hf ͘ as a function of the milling time for the studied samples. It can be noted that, as it was expected, samples with larger Fe content present a higher ͗B hf ͘ and that this field is larger for longer milling times.…”

“…This expansion was reported in ordered alloys produced by melting, 28 when they were mechanically grinded ͑MG͒ and then heat treated, [17][18][19][20][21][22] as well as in disordered melted alloys. 23 According to recent literature, 10,[16][17][18][19][20][21] the disorder and the lattice expansion observed in MG samples are jointly responsible for the enhancement of the F behavior and these effects are more notable for samples in the region between 40 and 50 at. % Al.…”

“…The Fe-Al alloys form a complete solid solution series that has been the subject of a large deal of research efforts due to ͑i͒ the rich variety of magnetic order types observable in the series, 1-11 ͑ii͒ the relevant role of disorder in the occurrence of those magnetic phases, 1,2,4,8,10-13 ͑iii͒ the observation of expansion effects whose link to the induction of magnetic order is not completely established, 8,[16][17][18][19][20][21] and ͑iv͒ the applicability of these alloys as structural and corrosion/ oxidation resistant materials.…”

Tuneable magnetic patterning of paramagnetic Fe60Al40 (at. %) by consecutive ion irradiation through pre-lithographed shadow masks

“…This thermal treatment is sufficient to convert the disordered A2 phase into the atomically ordered B2 structure. 28 A 90 nm-thick poly(methyl methacrylate) (PMMA) resist layer was then spin coated onto the Fe 60 Al 40 sheet surface and subsequently patterned using electron beam lithography to obtain arrays of circular dots, with diameters ranging from 225 to 420 nm. Consecutive ion irradiation through the PMMA shadow masks was carried out using Ar þ ions with a fluence of 1.2 Â 10 14 ions/cm 2 and progressively larger energies (10,13,16,19, and 22 keV), as illustrated in Fig.…”