NEUTRON-DIFFRACTION STUDY OF CECUGA3

Neutron-diffraction experiments have been performed on both polycrysta lline and single-crystal samples of CeCuGa3. The results of the powder diffraction experiments show that CeCuGa3 adopts an incommensurate ma gnetic structure at 1.25 K. The propagation wave vector associated wit h the magnetic ordering k(m) is (0.176, 0.176, 0), and the magnitude o f the magnetic moment in the ordered state is 1.24 +/- 0.02 mu(B). Sin gle-crystal neutron diffraction confirmed the existence of magnetic sa tellite peaks at Q values determined by the wave vector k(m). Addition al satellites have been observed in the single-crystal diffraction exp eriments with an incommensurate propagation vector of k(s) = (0.137, 0 .137, 0). These are probably the result of a short-ranged modulation o f the crystal structure.