Browsing by Author "Loh, NA"

Now showing 1 - 6 of 6
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    The fermi surface of Cu3Mn {100} and spinglass magnetism
    (Australian Institute of Physics, 2009-02-05) Stampfl, APJ; Loh, NA; Hsieh, KY; Yu, DH; Brigden, P; Stojanov, P; Riley, JD; Stamps, RL; Yuh, JY; Pi, TW; Chang, J; Hwu, YK
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    Investigation of field-induced ferromagnetism in Pd-Ni-Fe-P metallic glass by x-ray magnetic circular dichroism
    (American Institute of Physics, 2009-01-12) Yu, DH; Duriavig, J; Loh, NA; Woodward, RC; Lin, HJ; Chang, FH; Kilcoyne, SH; Stampfl, APJ; Robinson, RA
    We have applied x-ray magnetic circular dichroism to investigate the field-induced ferromagnetism in Pd40Ni22.5Fe17.5P20 alloy. The experiment revealed that both Ni and Fe were in a divalent state and that the magnetic properties of the material were determined by the localized 3d electrons of the transition metals. No clear evidence of Ruderman–Kittel–Kasuya–Yosida-type interaction among magnetic clusters was observed. It is believed that the detailed balance of fundamental spin-orbit and exchange interactions as a function of temperature and applied magnetic field determine the different magnetic properties of the alloy. © 2009, American Institute of Physics
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    The magnetism of CrO2 under high pressure
    (Australian Institute of Physics, 2009-02-04) Loh, NA; King-Lacroix, J; Yu, DH; Robertson, R; Stampfl, APJ; Tseng, YC; Haskel, D
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    Onset of biquadratic coupling in Co/CuMn multilayers studied with polarised neutron reflectivity
    (Australian Institute of Physics, 2009-02-05) Loh, NA; Saerbeck, T; Ali, M; Lott, D; Stampfl, APJ; Hickey, BJ; Toperverg, BP; Mulders, AM; Stamps, RL; Klose, F
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    Spatial fluctuations of loose spin coupling in CuMn/Co multilayers
    (American Physical Society, 2011-09-12) Saerbeck, T; Loh, NA; Lott, D; Toperverg, BP; Mulders, AM; Rodriguez, AF; Freeland, JW; Ali, M; Hickey, BJ; Stampfl, APJ; Klose, F; Stamps, RL
    A detailed investigation of magnetic impurity-mediated interlayer exchange coupling observed in Cu(0.94)Mn(0.06)/Co multilayers using polarized neutron reflectometry and magnetic x-ray techniques is reported. Excellent descriptions of temperature and magnetic field dependent biquadratic coupling are obtained using a variant of the loose spin model that takes into account the distribution of the impurity Mn ions in three dimensions. Positional disorder of the magnetic impurities is shown to enhance biquadratic coupling via a new contribution J(2)(fluct), leading to a temperature dependent canting of magnetic domains in the multilayer. These results provide measurable effects on RKKY coupling associated with the distribution of impurities within planes parallel to the interfaces.© 2011, American Physical Society
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    Temperature dependent biquadratic exchange coupling in Co/Cu (0.94)Mn(0.06) multilayers
    (Australian Institute of Physics, 2010-02-05) Saerbeck, T; Loh, NA; Ali, M; Hickey, BJ; Lott, D; Toperverg, BP; Mulders, AM; Stampfl, APJ; Klose, F; Stamps, RL
    Magnetic interlayer coupling phenomena in systems consisting of ferromagnetic films separated by non-magnetic spacer layers, such as Co/Cu multilayers, are heavily dependent on the thickness and composition of the spacer layer. Usual Co/Cu multilayers exhibit the normal oscillatory RKKY exchange coupling resulting in alternating ferromagnetic/antiferromagnetic magnetic alignment of adjacent layers with increasing Cu thickness. We report on a crucial temperature dependence of this coupling introduced as the non-magnetic spacer layer is substituted by a spin-glass material, such as CuMn. Kobayashi et al. first discovered the extraordinary behaviour of a ferromagnetic exchange coupled Co/CuMn multilayer structure showing an increasing antiferromagnetic component as the system is cooled below a critical temperature. In order to investigate the magnetic rearrangement throughout the transition temperature in more detail we used polarized neutron reflectometry in specular and off-specular geometry to resolve the orientation of the magnetization in the Co layers. Co/Cu(0.94)Mn(0.06) multilayer samples with a manganese concentration of 6at% in the spacer layer are grown using sputter deposition and quality checked with X-ray reflectivity and diffraction. The onset of a magnetic rearrangement into an antiferromagnetic constitution around 100K is confirmed by neutron reflectivity measurements, revealing the onset of biquadratic interlayer coupling. Simulations of the full two dimensional off-specular scattering points out each layer breaking into magnetic domains. Further magnetic characterisation of the sample using X-Ray magnetic circular dichroism and conventional magnetometry indicate the role of the Mn doping in the magnetic transition into a biquadratic coupling.