High field magnetization of single crystalline Ho/sub 2/Co/sub 17/ under pressure

High-field magnetization measurements up to 38 T have been performed on a-newly-grown single-crystalline Ho/sub 2/Co/sub 17/ sample along the main crystallographic directions of the hexagonal cell. The magnetization curve along the easy direction (b-axis) exhibits a metamagnetic-like transition at 23.6 T whereas for the a-axis a similar transition occurs at 32.4 T. The transitions are extremely sharp-much sharper than in previously grown crystals. The transitions are understood as a moment-flip transition associated with the formation of a noncollinear magnetic structure in this ferrimagnetic compound. From the transition-field value the 3d-4f spin-exchange parameter has been derived. Magnetization under pressure up to 5 kbar has been used to determine the pressure dependence of the magnetic transition at 23.6T. The pressure dependence dB/sub tr//dP amounts to -24 TMbar/sup -1/.<
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