In situ magnetic and structural analysis of epitaxial Ni80Fe20 thin films for spin-valve heterostructures

Abstract

We have investigated structural and magnetic properties of epitaxial (100) N&Feel0 films grown on relaxed Cu/Si(lOO) seed layers. The crystallographic texture and orientation of these films was analyzed in situ by reflection high energy electron diffraction (RHEED), and M situ by x-ray diffraction and cross-sectional transmission electron microscopy (XTEM). In particular, RHEED intensities were recorded during epitaxial growth, and intensity profiles across Bragg rods were used to calculate the surface lattice constant, and hence the film strain. XTEM analysis indicated that the epitaxial films had atomically abrupt interfaces The magnetic properties of these epitaxial films were measured in situ using magneto-optic Kerr effect magnetometry. Large N, (10-20 Oej was observed for epitaxial Nis,,Fez,, (100) films less than 10.0 nm thick whereas for larger thicknesses, W, decreased to a few Oe with the appearance of a uniaxial anisotropy. Correlations were made between magnetic properties of these epitaxial films and the strain in the film.

Effect of atomic ordering on the magnetic anisotropy of single crystal Ni80Fe20

“…induced uniaxial anisotropy. Single crystal Py films have been deposited epitaxially by numerous techniques, including thermal evaporation, 7,9,10 electron beam evaporation, 11 molecular beam epitaxy (MBE), [12][13][14] ion beam sputtering, 15,16 a) Electronic mail: mkk4@hi.is b) Electronic mail: tumi@hi.is c) Electronic mail: sthi@hi.is rf magnetron sputtering, 17,18 dc magnetron sputtering, 19 and pulsed laser deposition. 20 Most of these deposition methods have resulted in a single crystal Py (001) film on MgO (001) with biaxial anisotropy in the plane, and the easy directions being [110] or [100].…”

“…3,[21][22][23] Several groups have shown that an increase in atomic order results in deterioration of the anisotropy constant K 1 . 3,22,24,25 Uniaxial anisotropy can be induced in single crystal Py by applying an in-situ magnetic field during deposition, 7,15,16 or by post annealing 26 in magnetic field. It has been shown that magnetic field induced anisotropy strongly depends on the crystal orientation of the Py for both deposition and annealing in a magnetic field 7,27 i.e.…”

Magnetic properties and microstructures of Mn−Ir/Ni−Fe exchange biased multilayers on Ta and Cr buffer layers

“…In addition, epitaxial growth appeared at the interface between the Mn-Ir grain and the Ni-Fe grain, which was confirmed by the observation of continuous lattice fringes across the interface and XRD results. An important value that characterizes epitaxy is the lattice misfit, f, of the equation defined as f=(a(A)-a(B))/a(B) where a(A) and a(B) refer to unstrained lattice constants of overlayer B and substrate A [8]. Generally, a misfit value f of (0.1) between the lattice constants for A and B and the same crystal structure are demanded for the epitaxial growth between the A layer and the B layer [9].…”

Origin and properties of an unexpected exchange bias of Ta/Ni80Fe20/Ir20Mn80/Ta heterostructure in ultrathin limit: Impact of the oblique deposition and Ta/Ni80Fe20 alloying

“…The film thickness, below which the ultrathin limit is defined, can be obtained from anisotropy terms [28][29][30][31][32][33]. In the case of the N i80 Fe 20 alloy, an ultrathin limit thickness of 5 nm, at room temperature (RT), was calculated using its magnetic anisotropy parameters [34][35][36].…”