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Park, S.-W.*; 溝口 拓*; 樹神 克明; 社本 真一; 大友 季哉*; 松石 聡*; 神谷 利夫*; 細野 秀雄*
Inorganic Chemistry, 52(23), p.13363 - 13368, 2013/12
被引用回数:29 パーセンタイル:82.23(Chemistry, Inorganic & Nuclear)We report the synthesis, structure, and electromagnetic properties of Cr-based layered oxyarsenides LnCrAsO (Ln = La, Ce, Pr, and Nd) with a ZrCuSiAs-type structure. All LnCrAsO samples showed metallic electronic conduction. Electron doping in LaCrAsO by Mnsubstitution for the Cr sites gave rise to a metal-insulator transition. Analysis of powder neutron diffraction data revealed that LaCrAsO had Gtype antiferromagnetic (AFM) ordering, i.e., a checkerboard-type AFM ordering in the CrAs plane and antiparallel spin coupling between the adjacent CrAs planes, at 300 K with a large spin moment of 1.57 along the c axis. The magnetic susceptibility of LaCrAsO was very small (on the order of 10 emu/mol) and showed a broad hump at 550 K. First-principles density functional theory calculations of LaCrAsO explained its crystal structure and metallic nature well, but could not replicate the antiparallel spin coupling between the CrAs layers. The electronic structure of LaCrAsO is discussed with regard to those of related compounds LaFeAsO and LaMnAsO.
樹神 克明; 脇本 秀一; 井川 直樹; 社本 真一; 溝口 拓*; 細野 秀雄*
Physical Review B, 83(21), p.214512_1 - 214512_5, 2011/06
被引用回数:18 パーセンタイル:59.63(Materials Science, Multidisciplinary)We have performed powder neutron diffraction on the new superconductor, CeNiBi with a superconducting transition temperature 4.2 K. The structural parameters of this compound at room temperature are determined by Rietveld analysis. Below about 5 K, the clear magnetic Bragg peaks with propagation vector =(0 0 0) are observed. The observed intensities of magnetic Bragg peaks can be explained by the magnetic structure that the two Ce moments in the unit cell are antiparallel along the -axis. The magnetic Bragg peaks are observed in the superconducting state, indicating the coexistence of the antiferromagnetic ordering and the superconductivity in this compound. The intensity of magnetic Bragg peak monotonously increases with decreasing temperature below and does not exhibit apparant anomaly at , obviously different from cases of heavy fermion superconductors in which the magnetic ordering and the superconductivity coexist, for example, Cd-doped CeCoIn. These results suggest that the 4 electron of the Ce atom is not coupled with the superconducting carrier, and the magnetic ordering is almost independent of the superconductivity in CeNiBi.
樹神 克明; 脇本 秀一; 井川 直樹; 社本 真一; 溝口 拓*; 細野 秀雄*
no journal, ,
We have performed powder neutron diffraction on new superconductor, CeNiBi with superconducting transtion temperature 4.2 K. The structural parameters of this compound at room temperature are determined by Rietveld analysis. Below about 5 K, the clear magnetic Bragg peaks with propagation vector =(0 0 0) are observed. The observed intensities of magnetic Bragg peaks can be explained by the magnetic structure that the two Ce moments in the unit cell are antiparallel along axis. The magnetic Bragg peaks are observed in superconducting state, indicating the coexistence of the antiferromagnetic ordering and the superconductivity in this compound. The intensity of magnetic Bragg peak monotonously increases with decreasing temperature below and does not exhibit apparent anomaly at , obviously different from cases of heavy fermion superconductors in which the magnetic ordering and the superconductivity coexist, for example, Cd-doped CeCoIn. These results suggest that the 4 electron of Ce atom is not coupled with the superconducting carrier and the magnetic ordering is almost independent of the superconductivity in CeNiBi.