Characteristic Magnetic Structure due to Antiferroquadrupolar Ordering in Ho^<11>B_2C_2 : Condensed Matter: Electronic Properties, etc.

概要

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We determined the magnetic structures of the antiferroquadrupolar (AFQ) ordering material with a tetragonal crystal structure, Ho^<11>B_2C_2, by neutron diffraction technique. The ground state of Ho^<11>B_2C_2 below T_Q shows a characteristic magnetic structure due to competitive coexistence of AFQ and antiferromagnetic (AFM) interactions, which is basically the same as that of the other tetragonal AFQ material DyB_2C_2. An angle of 70° between adjacent magnetic moments along [001] indicates that the main component of magnetic couplings along [001] in the ground state is ferromagnetic one, which is strongly affected by AFQ interactions. The existence of the intermediate magnetic ordered phase, phase IV, above T_Q indicates that the AFQ ordering in HoB_2C_2 at T_Q is a rare case which is realised in a magnetic ordered state. The magnetic structure in phase IV is a long period one caused by a short range magnetic ordering with a characteristic energy of about 9 K which is higher than T_N. The suppressed magnetic entropy at TN is, therefore, attributed to the short range magnetic ordering.
社団法人日本物理学会の論文
2000-10-15