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Sakai, Hironori; Hattori, Taisuke; Tokunaga, Yo; Kambe, Shinsaku; Ueda, Hiroaki*; Tanioku, Yasuaki*; Michioka, Chishiro*; Yoshimura, Kazuyoshi*; Takao, Kenta*; Shimoda, Aiko*; et al.
Physical Review B, 98(6), p.064403_1 - 064403_10, 2018/08
Times Cited Count:10 Percentile:45.99(Materials Science, Multidisciplinary)To specify preferential occupation sites of Co substituents and to clarify charge and spin states of Co ions in (La, Co)-cosubstituted hexagonal magnetoplumbite-type (M-type) Sr ferrite, Fe and Co nuclear magnetic resonance (NMR) spectra are measured under zero and external magnetic fields using powdered and single crystalline specimens. To a considerable degree, the charge compensation between La and Co works in the equal (La, Co)-codoped case, where more than half of the Co ions are considered to be present in the minority spin sites at the center of the oxygen tetrahedra, with the = 3/2 state carrying a small orbital moment owing to spin-orbit interaction. The remaining small number of high-spin Co ( = 3/2, = 1) ions with unquenched orbital moments would be distributed to the other octahedral , , and sites.
Koyama, Takehide*; Ozaki, Yuzuru*; Ueda, Koichi*; Mito, Takeshi*; Kohara, Takao*; Waki, Takeshi*; Tabata, Yoshikazu*; Michioka, Chishiro*; Yoshimura, Kazuyoshi*; Suzuki, Michito; et al.
Journal of the Physical Society of Japan, 81(Suppl.B), p.SB008_1 - SB008_5, 2012/12
Times Cited Count:1 Percentile:10.8(Physics, Multidisciplinary)The normal state properties of a noncentrosymmetric superconductor MoAlC are studied by means of the nuclear magnetic resonance (NMR) experiment. The change of NMR line shape and the peak of the nuclear spin-echo decay rate at 130 K indicate that the MoAlC exhibits the phase transition prior to the emergence of superconductivity. The reduction in the conduction electron density is inferred from the decrease in the nuclear spin-lattice relaxation rate. The nature of the newly found phase transition is discussed by considering the result of the first principle calculations, indicating a good nesting property of the Fermi surfaces.
Koyama, Takehide*; Ozaki, Yuzuru*; Ueda, Koichi*; Mito, Takeshi*; Kohara, Takao*; Waki, Tsuyoshi*; Tabata, Yoshikazu*; Michioka, Chishiro*; Yoshimura, Kazuyoshi*; Suzuki, Michito; et al.
Physical Review B, 84(21), p.212501_1 - 212501_4, 2011/12
Times Cited Count:12 Percentile:44.66(Materials Science, Multidisciplinary)The results of Al nuclear magnetic resonance and specific-heat measurements of the noncentrosymmetric superconductor MoAlC are reported. The phase transition around 130 K is inferred from a distinct change in the NMR spectrum, a clear peak in the spin-echo decay rate, and an anomaly in the specific heat. Possibility of charge-density wave ordering around 130 K is discussed by calculating the Fermi surfaces in the normal states and considering the partial quenching of the Fermi surfaces with the decrease in 1/ below the superconducting transition temperature.
Sakai, Hironori; Hattori, Taisuke; Tokunaga, Yo; Kambe, Shinsaku; Shimoda, Aiko*; Waki, Takeshi*; Tabata, Yoshikazu*; Nakamura, Hiroyuki*
no journal, ,
Zero field NMR experiments on SrFeO and SrLaFeCoO have been performed. The substitued Co sites will be discussed based on the NMR spectra.
Sakai, Hironori; Hattori, Taisuke; Tokunaga, Yo; Kambe, Shinsaku; Shimoda, Aiko*; Waki, Takeshi*; Tabata, Yoshikazu*; Nakamura, Hiroyuki*
no journal, ,
Zero field NMR experiments have been done using powdered samples and single crystals of SrFeO and La-Co co-substituted SrLaFeCoO. The single crystals were grown by the flux method. Co NMR signals have been observed in the lower frequency range of 50-100 MHz and in the higher frequency range of 300-400 MHz. Spectral intensity in the lower frequency range is stronger than that in the higher frequency range. We will discuss the spin and charge states of Co ions using the NMR results, some complementary experiments and theoretical considerations.
Sakai, Hironori; Hattori, Taisuke; Tokunaga, Yo; Kambe, Shinsaku; Shimoda, Aiko*; Waki, Takeshi*; Tabata, Yoshikazu*; Nakamura, Hiroyuki*
no journal, ,
Fe and Co NMR spectra have been observed for La-Co co-substituted M-type Ferrite. We will microscopically discuss about the Co sites in the co-substituted M-type Ferrite as well as spin and charge states of Co ions.
Sakai, Hironori; Hattori, Taisuke; Tokunaga, Yo; Kambe, Shinsaku; Shimoda, Aiko*; Waki, Takeshi*; Tabata, Yoshikazu*; Nakamura, Hiroyuki*
no journal, ,
We will discuss about the Co sites and the electronic states of Co ions in La-Co co-substituted SrFeO using the Fe and Co NMR results.