Transport Properties of Ce_2Co_7B_3 in Magnetic Field(Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties)

概要

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Thermopower S, resistivity ρ and magnetization M of Ce_2Co_7B_3 have been measured in magnetic fields up to 15T at temperature range from 2 to 1000K. The magnetic field dependence of S(H) and ρ(H) changes drastically at spin-flop critical field H_s=6.0T in 4.2K. A very large negative magnetoresistance is observed, 35% in 15T at 4.0K, suggesting large spin-spin interaction between s and d electrons. Magnetic phase transitions in temperature and field are experimentally obtained, a magnetic phase diagram is established. The S(T) measured up to 1000K suggests that a DOS peak exists at 250K apart from Fermi level (ε_F) in energy. Below H_s, a negative peak exists on the S(T) curve around 20K, which disappears suddenly at H_s. The negative peak is estimated coming from a super-zone boundary on ε-k curve caused by anti-ferromagnetic periodicity. The DOS below and above H_s have been estimated from experimental S(T) in terms of Mott's two band s-d scattering model.
社団法人日本物理学会の論文
2006-04-15