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Magnetic and magneto-optical studies on manganese-based compounds
Abstract
Thin films of $\rm Mn\sb{x}Pt\sb{1-x}$ (x = 0.18, 0.22, 0.25, 0.30, 0.34) were prepared by magnetron sputtering onto quartz substrates. After annealing the films form a highly-ordered cubic structure where the magnetic atoms occupy the cube corners and the Pt atoms the face-centered sites, and as x increased from 0.25 there is a continuous change in lattice parameters. Presented are the results of magnetic and magneto-optical measurements on these samples over a wide range of temperatures. It is found that the magnetic properties are strongly dependent on composition and temperature. Also a detailed investigation of the electronic structure of MnPt$\sb3$ via both experimental and theoretical studies of its complex dielectric tensor is carried out. Mn-Pt alloys are known to undergo a transition from the cubic to a tetragonal structure for x $>$ 0.38; unfortunately, the increased number of antiferromagnetic Mn-Mn nearest-neighbor interactions for x $>$ 0.25 induces a complex non-collinear magnetic structure. Thus one of our goals was to substitute a third non-magnetic element into the Mn-Pt alloy to develop a ferromagnetic tetragonal structure. To this end ferromagnetic ternary alloys of $\rm Mn\sb{x}Pt\sb{1-x-y}Zn\sb{y}$ were produced by magnetron sputtering over a wide composition range (x = 0.17 $-$ 0.34, y = 0.00 $-$ 0.13), and their magnetic and magneto-optic properties were studied. The magnetic properties of annealed thin film samples of $\rm MnBi\sb{0.8}Al\sb{x}$ (x = 0.0, 0.4, 0.6, 0.8) were systematically studied over a temperature range of 20 to 300K. Our measurements show that the coercivity of such films rapidly decreases than approaches a constant value ((4 kOe) for x = 0.4) with increasing annealing time. Magnetic measurements show that both anisotropy and coercivity decrease with decreasing temperature.
Subject Area
Condensation|Materials science
Recommended Citation
Wierman, Kurt W, "Magnetic and magneto-optical studies on manganese-based compounds" (1996). ETD collection for University of Nebraska-Lincoln. AAI9703796.
https://digitalcommons.unl.edu/dissertations/AAI9703796