Jungho Kim et al 2007 J. Phys.: Condens. Matter 19 106203 doi:10.1088/0953-8984/19/10/106203
Jungho Kim1, SungHoon Jung2, J H Noh2, B K Cho3 and E J Choi2,4
Show affiliationsWe have studied the magnetic and optical properties of hexaboride Eu1−xCaxB6 for x = 0, 0.13, 0.25, 0.35, 0.54 and 1.0 from measurements of dc magnetization and wide-range absolute reflectivity. The ferromagnetic transition temperature Tc decreases with Ca-doping and is completely suppressed when x exceeds 0.35. The Drude plasma frequency ωp2 also decreases with x and disappears at the same composition. We have analysed this correlation between Tc and ωp2 in terms of the RKKY theory. We have also simulated optical spectra of Eu1−xCaxB6 using the effective medium theory and compare them with the measured data. The results show that Eu1−xCaxB6 is not a composite of EuB6 and CaB6 but forms a homogeneous magnetic alloy.
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
Issue 10 (14 March 2007)
Received 5 October 2006, in final form 24 January 2007
Published 15 February 2007
Jungho Kim et al 2007 J. Phys.: Condens. Matter 19 106203
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