Neutron Scattering Study on Competition between Hidden Order and Antiferromagnetism in U(Ru_<1-x>Rh_x)_2Si_2 (x ≤ 0.05) (Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties)

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We have performed elastic and inelastic neutron scattering experiments on solid solutions of U(Ru_<1-x>Rh_x)_2Si_2 with Ru-rich concentrations: x = 0, 0.01, 0.02, 0.025, 0.03, 0.04 and 0.05. Hidden order is suppressed with increasing x, and correspondingly, the onset temperature T_m (〜 17.5 K at x = 0) of weak antiferromagnetic (AF) Bragg reflection decreases. For x = 0.04 and 0.05, no magnetic order is detected in the investigated temperature range down to 1.4 K. In the intermediate range, 0.02 ≤ x ≤ 0.03, we found that the AF Bragg reflection is strongly enhanced. At x = 0.02, this enhancement takes place at 〜 7.7K (≡ T_M), which is significantly lower than T_m (〜 13.7 K). T_M increases with increasing x, and seems to merge with T_m at x = 0.03. If the AF state is assumed to be homogeneous, the staggered moment μ_o estimated at 1.4 K increases from 0.02(2)μ_B/U (x = 0) to 0.24(1) μ_B/U (x = 0.02). The behavior is similar to that observed under hydrostatic pressure (μ_o increases to 〜0.25 μ_B/U at 1.0 GPa), suggesting that the AF evolution induced by Rh doping is due to an increase in the AF volume fraction. We also found that the magnetic excitation observed at Q = (1, 0, 0) below T_m disappears as T is lowered below T_M.
社団法人日本物理学会の論文
2004-03-15