On defects’ role in enhanced perpendicular magnetic anisotropy in Pt/Co/Pt, induced by ion irradiation

Abstract

Modifications of magnetic and magneto-optical properties of Pt/Co(dCo)/Pt upon Ar+ irradiation (with energy 1.2, 5 and 30 keV) and fluence, F at the range from 2 · 1013–2 · 1016 Ar+ cm−2) were studied. Two ‘branches’ of increased perpendicular magnetic anisotropy (PMA) and enhanced magneto-optical response are found on 2D (dCo, F) diagrams. The difference in F between ‘branches’ is driven by ion energy. Structural features correlated with magnetic properties have been analysed thoroughly by x-ray diffraction, Rutherford backscattering spectrometry and positron annihilation spectroscopy. Experimental results are in agreement with TRIDYN numerical calculations of irradiation-induced layers intermixing. Our work discusses particularly structural factors related to crystal lattice defects and strain, created and modified by irradiation, co-responsible for the increase in the PMA.

Magnetic Domains without Domain Walls: A Unique Effect of He+ Ion Bombardment in Ferrimagnetic Tb/Co Films

“…Since the DW energy released by these processes is proportional to the wall interface area, this reduction of H S 23 (H S 41 ) with decreasing a is understandable. Additionally, it is obvious that a reduction of a produces a broadening of the transition region for the switching fields H S 23 and H S 41 . This is related to the statistical variation of H S among the squares (see movie in supplementary materials).…”

“…Hereinafter, the switching fields H S if , related to the transition between specific states will be described using superscripts identifying the initial (i) and final (f) states, e.g., for D = 110 15 He + /cm 2 (Fig. 3a) H S 23 and H S 41 corresponds to the magnetization reversal of areas (squares) subjected to ion bombardment. At this dose D, both the matrix and the squares show the dominance of the magnetic moments of the Tb magnetic subsystem.…”

“…Domain patterns can be engineered by local modification of magnetic properties such as the coercive field (H C ) [14][15][16][17] or the exchange bias coupling of systems composed of ferromagnetic and antiferromagnetic layers [18][19][20][21]. In the past this has been achieved, e.g., by light-ion bombardment through masks [18][19][20]22,23], by focused ion beams [24][25][26][27], by direct laser writing [28], or by thermally assisted scanning probe lithography [29]. Walls between magnetic domains engineered by these methods are usually non-symmetric [30] with respect to their center due to different anisotropies on the two sides of the wall.…”

Ar+ ion irradiation of magnetic tunnel junction multilayers: impact on the magnetic and electrical properties

“…MTJ multilayer stacks were prepared by dc magnetron sputtering on thermally oxidized 8inch Si wafers. The structure of the stacks is Si / SiO2 / Ta(3) / CuN(30) / Ta(5) / Ru(2) / IrMn(12) / PL(2) / Ru(0.8) / RL(2.3)/ MgO(1.5) / FL( FL t ) / Ta(5) / Ru (7), where PL, RL and FL are, respectively, the pinned, reference and free layer, made of FeCo(B) alloys. The numbers in parentheses are nominal thicknesses in nanometers.…”

Enhanced Spin Hall Effect in S‐Implanted Pt

“…[15][16][17][18][19][20][21][22] For example, SH is shown to be improved marginally from 0.044 to 0.059 by oxygen incorporation in Pt [13] whereas rigorously studied Pt-based alloys in combination to a variety of FM showed wide distribution in SH values (in parentheses) like Pt 53 Au 47 /Ni 80 Fe 20 (NiFe) (0.33 ± 0.09), [15] Pt 75 Au 25 /Co (0.35), [16] Pt 75 Pd 25 /Fe 0.6 Co 0.2 B 0.2 (0.26 ± 0.02), [17] Pt 45 Pd 55 /NiFe (0.06), [18] Pt 90 Pd 10 /Y 3 Fe 5 O 12 (0.17), [19] Pt 85 Hf 15 /Co (0.16 ± 0.01), [20] Pt 92 Bi 8 /Y 3 Fe 5 O 12 (0.106 ± 0.005), [21] and Pt 28 Cu 72 /NiFe (0.07 ± 0.002). [22] However, in this respect, ion implantation or irradiation-based engineering is not studied to tune the conversion efficiency of Pt despite being capable of molding spin-based properties such as local control of magnetization dynamics in NiFe/Pt, [23] enhanced perpendicular anisotropy in Pt/Co/Pt, [24] and reduced critical current for switching in Pt/Co/Ta. [25] Here, we report a new SHM fabricated by using non-metallic sulfur-ion (S-ion) implantation in Pt, hereafter referred to as Pt(S), at low energy of 12 keV with 5 × 10 16 ions cm -2 dosage.…”