Study of ultrathin Pt/Co/Pt trilayers modified by nanosecond XUV pulses from laser-driven plasma source

We have studied the structural mechanisms responsible for the magnetic reorientation between in-plane and out-of-plane magnetization in the (25 nm Pt)/(3 and 10 nm Co)/(3 nm Pt) trilayer systems irradiated with nanosecond XUV pulses generated with laser-driven gas-puff target plasma source of a narrow continuous spectrum peaked at wavelength of 11 nm. The thickness of individual layers, their density, chemical composition and irradiation-induced lateral strain were deduced from symmetric and asymmetric X-ray diffraction (XRD) patterns, grazing-incidence X-ray reflectometry (GIXR), grazing incidence X-ray fluorescence (GIXRF), extended X-ray absorption fine structure (EXAFS) and transmission electron microscopy (TEM) measurements. In the as grown samples we found, that the Pt buffer layers are relaxed and that the layer interfaces are sharp. As a result of a quasi-uniform irradiation of the samples, the XRD, EXAFS, GIXR and GIXRF data reveal the formation of two distinct layers composed of Pt1-xCox alloys with different Co concentrations, dependent on the thickness of the as grown magnetic Co film but with similar ∼1% lateral tensile residual strain. For smaller exposure dose (lower number of accumulated pulses) only partial interdiffusion at the interfaces takes place with the formation of a tri-layer composed of Co-Pt alloy sandwiched between thinned Pt layers, as revealed by TEM. The structural modifications are accompanied by magnetization changes, evidenced by means of magneto-optical microscopy. The difference in magnetic properties of the irradiated samples can be related to their modification in Pt1-xCox alloy composition, as the other parameters (lateral strain and alloy thickness) remain almost unchanged. The out-of-plane magnetization observed for the sample with initially 3 nm Co layer can be due to a significant reduction of demagnetization factor resulting from a lower Co concentration

The Improvement of Atomic Force Microscope Suitable for Magnetic Domain Structure Measurements

Based on commercial Burleigh METRIS$\text{}^{TM}$-2000 Atomic Force Microscope two methods of magnetic force measurements were realised. The developed system was successfully applied for study of magnetic structure of both YIG-garnet and CoNi/Pt magneto-optic multilayers

Two-dimensional Green's functions for fluid and thermoelastic two-phase plane

The two-dimensional Green's functions for a steady-state line heat source in the interior of fluid and thermoelastic two-phase plane are derived in this paper. By virtue of the compact two-dimensional general solutions which are expressed in harmonic functions, four newly introduced harmonic functions with undetermined constants are constructed. Then, all the thermoelastic components in the fluid and thermoelastic two-phase plane can be derived by substituting these harmonic functions into the corresponding general solutions. And the undetermined constants can be obtained by the corresponding conditions of compatibility, boundary and equilibrium. Numerical results are given graphically by contours

The Influence of He +

The influence of $He^+$ ion bombardment on magnetoresistance, magnetization reversal and domain structure of sputtered $(Ni_{80}Fe_{20}(2 nm)//Au(2 nm)//Co(0.6 nm)//Au(2 nm))_{10}$ multilayers was investigated. The samples were bombarded using $He^+$(30 keV) ions with fluences D varied from $10^{13}$ to 3×$10^{16}$ $He^+$/$cm^{2}$. With increasing D the following changes in magnetic properties were observed: (i) exponential decay of the saturation field of Co layers, (ii) progressive decrease in magnetoresistance as a result of degradation of Co layers perpendicular anisotropy, (iii) linear decrease in stripe domain period with log(D)

The Influence of He+He^+ Ion Bombardment on Magnetic Properties of NiFe/Au/Co/Au Multilayers

The influence of $He^+$ ion bombardment on magnetoresistance, magnetization reversal and domain structure of sputtered $(Ni_{80}Fe_{20}(2 nm)//Au(2 nm)//Co(0.6 nm)//Au(2 nm))_{10}$ multilayers was investigated. The samples were bombarded using $He^+$(30 keV) ions with fluences D varied from $10^{13}$ to 3×$10^{16}$ $He^+$/$cm^{2}$. With increasing D the following changes in magnetic properties were observed: (i) exponential decay of the saturation field of Co layers, (ii) progressive decrease in magnetoresistance as a result of degradation of Co layers perpendicular anisotropy, (iii) linear decrease in stripe domain period with log(D)

Material selective sensitivity of magneto-optical Kerr effect in NiFe/Au/Co/Au periodic multilayers

Material selective sensitivity of a magneto-optical polar Kerr effect to magnetizations of films from different materials in a multilayer system is presented. The method is supported by rigorous modeling of magneto-optic response from the multilayer system and by experimental demonstration on the periodic cobalt-permalloy multilayers [Ni80Fe20(2 nm)/Au(2 nm)/Co(0.4, 0.8, and 1.2 nm)/Au(2 nm)]10

Ga

Ga+ ion irradiation-induced changes in magnetic anisotropy of a Pt/Co/Pt ultrathin film are investigated by means of the X-ray magnetic circular dichroism (XMCD) technique. A large difference in the Co orbital moment is observed between out-of-plane and in-plane directions of the film at moderate Ga+ fluences of ~1-2×1014 ions/cm2, which corresponds to the perpendicular magnetic anisotropy (PMA), while further increased fluences reduce the orbital moment difference, resulting in in-plane magnetization. In contrast, at much higher Ga+ fluences of ~5×1015 ions/cm2, at which PMA is observed again, no significant difference is found in the orbital moment of Co between out-of-plane and in-plane directions. Different origins are thus suggested for the appearance of PMA induced by the irradiation between moderate and high Ga+ fluences

Ga+ ion irradiation-induced changes in magnetic anisotropy of a Pt/Co/Pt thin film studied by X-ray magnetic circular dichroism

Ga+ ion irradiation-induced changes in magnetic anisotropy of a Pt/Co/Pt ultrathin film are investigated by means of the X-ray magnetic circular dichroism (XMCD) technique. A large difference in the Co orbital moment is observed between out-of-plane and in-plane directions of the film at moderate Ga+ fluences of ~1-2×1014 ions/cm2, which corresponds to the perpendicular magnetic anisotropy (PMA), while further increased fluences reduce the orbital moment difference, resulting in in-plane magnetization. In contrast, at much higher Ga+ fluences of ~5×1015 ions/cm2, at which PMA is observed again, no significant difference is found in the orbital moment of Co between out-of-plane and in-plane directions. Different origins are thus suggested for the appearance of PMA induced by the irradiation between moderate and high Ga+ fluences