Magnetic Phase Transitions in Pure and Cobalt-Doped Geometrically Frustrated Ni3V2O8 Single Crystals |
| H. Szymczak, M. Baran, R. Szymczak
Institute of Physics, Polish Academy of Sciences, al. Lotników 32/46, 02-668 Warsaw, Poland S.N. Barilo, G.L. Bychkov and S.V. Shiryaev Institute of Solid State and Semiconductor Physics, NAS, P. Brovki 17, 220072 Minsk, Belarus |
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| Received: 04 09 2006; |
| The results of magnetic measurements performed on geometrically frustrated Ni3V2O8 and Ni3(1-x)Co3xV2O8 single crystals with x=0.03 are presented. It was found that Co doping did not change considerably the magnetic H-T phase diagram. Although no spin-glass effects were observed, nevertheless, a strong effect of 3 at% cobalt doping was evidenced. The main effect of Co-doping concerns the direction of the antiferromagnetic vector, which for Ni3V2O8 appears along the a axis, while for only slightly Co doped crystals - along the c axis. This switching of direction results from distinct changes of the magnetocrystalline anisotropy due to the presence of Co2+ ions strongly coupled to the kagome lattice. The disorder introduced by doping has practically no effect on the magnitude of the isotropic exchange interactions. At the same time the doping suppresses the Dzyaloshinskii-Moriya exchange interactions due to the change of direction of the antiferromagnetic vector. |
| DOI: 10.12693/APhysPolA.111.71 PACS numbers: 75.30.Gw, 75.30.Kz, 75.40.Cx, 75.50.-y |