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Dynamic magnetic susceptibility of Gd5Si2Ge2 and Gd4YSi1.9Ge2.1.

Authors :: Vecchini, C.
Moze, O.
Pecharsky, A. O.
Gschneider Jr., K. A.
Brück, E.
Bewley, R.
Kolesnikov, A.
Pecharsky, V. K.
Source :: Journal of Applied Physics; 6/1/2004, Vol. 95 Issue 11, p7207-7209, 3p, 1 Chart, 3 Graphs
Publication Year :: 2004
Abstract: The effects of diluting Gd with Y on the magnetic properties of the giant magnetocaloric effect material Gd<subscript>5</subscript>Si<subscript>2</subscript>Ge<subscript>2</subscript> have been investigated by high incident energy inelastic neutron scattering, magnetization, and x-ray powder diffraction measurements. The dynamic response for Gd<subscript>5</subscript>Si<subscript>2</subscript>Ge<subscript>2</subscript> at 15 and 150 K consists of two magnetic excitations extending up to 40 meV. From the x-ray powder diffraction data, Gd<subscript>4</subscript>YSi<subscript>1.9</subscript>Ge<subscript>2.1</subscript> is monoclinic at room temperature, space group P112<subscript>1</subscript>/a with the 4e site at x=-0.0092(3), y=0.1005(2), z=0.1808(4) almost exclusively occupied by Gd (97%), while the remaining four Gd/Y sites are randomly occupied by Gd and Y. The magnetization measurements show that the ordering temperature of Gd<subscript>4</subscript>YSi<subscript>1.9</subscript>Ge<subscript>2.1</subscript> is about half that of Gd<subscript>5</subscript>Si<subscript>2</subscript>Ge<subscript>2</subscript>, as the former orders ferromagnetically at 149 K with an effective paramagnetic moment of 7.87μ<subscript>B</subscript>. The observed magnetic dynamic response for the Gd<subscript>4</subscript>YSi<subscript>1.9</subscript>Ge<subscript>2.1</subscript> at 7 K is also different from the nondiluted compound, whereby the positions and intensities of the magnetic excitations have decreased markedly with respect to Gd<subscript>5</subscript>Si<subscript>2</subscript>Ge<subscript>2</subscript>. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]