Colossal negative thermal expansion induced by magnetic phase competition on frustrated lattices in Laves phase compound (Hf, Ta)Fe-2

Article

关键词: INITIO MOLECULAR-DYNAMICS;    AUGMENTED-WAVE METHOD;    POWDER DIFFRACTOMETER;    TRANSPORT-PROPERTIES;    HF1-XTAXFE2;    DIFFRACTION;    TRANSITIONS;    TIFE2;    OPAL;   

DOI  :  10.1103/PhysRevB.93.224405

来源: SCIE

【 摘 要 】

Competition between ferromagnetic and antiferromagnetic phases on frustrated lattices in hexagonal Laves phase compound Hf0.86Ta0.14Fe2 is investigated by using neutron diffraction as a function of temperature and magnetic fields and density-functional-theory calculations. At 325 K, the compound orders into the 120 degrees frustrated antiferromagnetic state with a well-reduced magnetic moment, and an in-plane lattice contraction simultaneously sets in. With further cooling down, however, the accumulated distortion in turn destabilizes this susceptible frustrated structure. The frustration is completely relieved at 255 K when the first-order transition to the ferromagnetic state takes place, where a colossal negative volumetric thermal expansion, -123 x 10(-6)/K, is obtained. Meanwhile, the antiferromagnetic state can be suppressed by few-tesla magnetic fields, which results in a colossal positive magnetostriction. Such delicate competition is attributed to the giant magnetic fluctuation inherent in the frustrated antiferromagnetic state. Therefore, the magnetoelastic instability is approached even under a small perturbation.

【 授权许可】

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