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College Park, Maryland      June 6 - 10 , 2004

T1-C3 (9:15 AM): Neutron Scattering Study of TbPtIn Intermetallic Compound

V. O. Garlea, J.L. Zarestky, E. Morosan, S.L. Budíko, P.C. Canfield, C. Stassis (Ames Laboratory and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011)

Neutron diffraction techniques have been used to study the magnetic properties of TbPtIn as a function of temperature and magnetic field. The measurements were performed on single crystals, using the HB1A triple-axis spectrometer at the High Flux Isotope Reactor (HFIR). This compound crystallizes in the hexagonal ZrNiAl-type structure and can be described as the alternate stacking of Tb-Pt and In-Pt layers perpendicular to the c-axis. The rare-earth sites form a triangular lattice; in the case of antiferromagnetic coupling between nearest neighbors, this topology induces a frustration of the magnetic interaction. In the absence of an externally applied magnetic field, the compound orders, below approximately 47 K, in an antiferromagnetic structure with propagation vector k = (½, 0, ½). The magnetic moments were found to be along the [1-20] symmetry direction by measurements in the plane defined by the [101] and [1-20] directions. Measurements performed in the a-c plane, at 4.2 K, with a magnetic field applied along the [1-20] direction, reveal a transition from the zero field antiferromagnetic state to a state with a net ferromagnetic component, at approximately 2 T, followed by another transition to a state with a larger ferromagnetic component, at approximately 4 T. Field cooled and zero field cooled measurements were also performed with the magnetic field applied along the [-110] direction, perpendicular to the direction of the magnetic moments. Two transitions were observed: one at 2 T and the other at 5.5 T. Of particular interest is the fact that above the second transition, at 5.5 T, and up to 6.8 T, we did not observe any antiferromagnetic reflections or appreciable changes in the nuclear reflections. Models of the magnetic structure are used in the analysis of the experimental data.

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