Preparation and Properties of Eutectic Bi-MnBi Single Crystals

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Abstract
Single crystals of Bi containing ordered MnBi filaments (∼4% by volume) have been grown by a zone‐melting technique in the presence of a longitudinal magnetic field. Metallographic and x‐ray examinations showed that the long axis of the MnBi needles (∼4 μ in diameter and ∼200 μ long) was aligned along the preferred growth direction, which is perpendicular to the trigonal axis, of the single crystalline Bi matrix. The long axis of the needles is the c axis of MnBi, the direction of easy magnetization. These needles rendered the eutectic Bi‐MnBi crystal ferromagnetic with a strong magnetic anisotropy, as revealed by magnetic moment measurements. The dependences on temperature and magnetic field of its electrical and thermal properties were essentially the same as those of pure Bi, which is a nonmagnetic semimetal. Thus, a controlled growth technique has been used here to achieve an ordered structural arrangement that combines the properties of semimetals and ferromagnetics into a single material.