ACTA

Magnetism in UCo_0.88Ru_0.12Ge Studied by Polarized Neutrons

M. Vališka^a, J.Pospíšil^a, G. Nénert^b, A. Stunault^b, K. Prokeš^c, V. Sechovský^a
^aFaculty of Mathematics and Physics, Charles University, DCMP, Ke Karlovu 5, CZ-12116 Praha 2, Czech Republic
^bInstitut Laue Langevin, 6 rue Jules Horowitz, 38042 Grenoble, France
^cHZB Berlin, Hahn-Meitner Platz 1 14109 Berlin, Germany

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UCoGe is an archetype of coexisting weak itinerant 5f-electron ferromagnetism (T_C ~ 3 K, μ_s=0.03μ_B/f.u.) and superconductivity (T_SC ~ 0.6 K) at ambient pressure. The Ru substitution for Co leads to an initial sharp increase of the T_C up to the maximum of T_C=8.5 K for x=0.12, increase of spontaneous magnetic moment and suppression of superconductivity. We have grown the UCo_0.88Ru_0.12Ge single crystal and studied magnetization along the principal crystallographic axes. To see the microscopic background of these findings we performed a polarized neutron diffraction experiment on D3 diffractometer in ILL. We have found that the Co and U moments are parallel in UCo_0.88Ru_0.12Ge, in contrast to the antiparallel configuration in UCoGe. This is probably the reason of the spontaneous magnetization increase with Ru doping.

DOI: 10.12693/APhysPolA.126.330
PACS numbers: 74.70.Tx, 61.05.fm, 75.25.-jr