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中島 多朗*; 満田 節生*; 稲見 俊哉; 寺田 典樹*; 大隅 寛幸*; Prokes, K.*; Podlesnyak, A.*
Physical Review B, 78(2), p.024106_1 - 024106_10, 2008/07
被引用回数:34 パーセンタイル:77.33(Materials Science, Multidisciplinary)We have performed synchrotron X-ray and neutron diffraction measurements on magnetoelectric multiferroic CuFeAlO (x=0.0155), which has a proper helical magnetic structure with incommensurate propagation wave vector in the ferroelectric phase. The present measurements revealed that the ferroelectric phase is accompanied by lattice modulation with a wave number 2, where is the magnetic modulation wave number. We have calculated the Fourier spectrum of the spatial modulations in the local electric polarization using a microscopic model proposed by T. Arima. Comparing the experimental results with the calculation results, we found that the origin of the 2-lattice modulation is the variation in the metal-ligand hybridization between the Fe ions and O ions. Combining the present results with the results of a previous polarized neutron diffraction study, we conclude that the microscopic origin of the ferroelectricity in CuFeAlO is the variation in the metal-ligand hybridization with spin-orbit coupling.
Pospisil, J.; 芳賀 芳範; 山本 悦嗣; 竹田 幸治; 岡根 哲夫; 山上 浩志*; Valika, M.*; Stunault, A.*; Gillon, B.*; Prokes, K.*; et al.
no journal, ,
We present that Ru substitution on the Co site in UCoGe leads to an initial sharp increase of the Curie temperature TC up to the maximum of 8.5 K for 12 of dopant. Further increase of the Ru content leads to the suppression of both the TC and spontaneous magnetic moment. Hand in hand with ferromagnetism increase suppression of superconductivity appears. Concentration dependence of the critical exponents of resistivity and heat capacity together with scaling of the TC has signs of the non-Fermi liquid (nFL) behavior around 30 of Ru. Latter performed PND and XMCD experiments assign ferromagnetism enhancement to growth of uranium orbital moment and mainly to dramatic transformation in Co sublattice. In contrast to parent UCoGe, we found parallel orientation of the U and Co moments in UCoRuGe and UCoRuGe single crystals.