Pioneering work of the mechanism elucidation of a new type ferromagnet Ca(La)B_6 by ESR.

2000年2月，在《自然》杂志上发表了一种新型铁磁体Ca（La）B_6的惊人论文。从那时起，出现了许多理论论文，但没有出现实验论文。原因是样品制备非常困难，因为熔点非常高（-2，500 ℃），并且液相和气相共存。我们克服了上述问题，成功地用铝助熔剂法制备了Ca（La）B_6单晶。在日本首次发现Ca（La）B_6的铁磁性。此外，我们还用电子自旋共振（ESR）研究了其铁磁性的形成机制。也就是说，由于铁磁性的自旋被各向异性场强烈地强制留在盘平面中。结果表明，Ca（La）B_6中的自旋仅存在于约1.5 μm厚的表面层中，具有较强的易平面型表面磁各向异性。

The surprising paper of a new-type of ferromagnet Ca(La)B_6 was reported in "Nature" at February,2000. There were many theoretical papers appeared since then, but an experimental paper was not appeared. The reason was that the sample preparation was very difficult, because the melting point is very high (-2,500℃), and the liquid phase and the gas phase are co-existing. We are overcoming the above problems, we succeeded the single crystals of Ca(La)B_6 by Aluminum-flux method. We found out, first time, the ferromagnetism of Ca(La)B_6 in Japan. Moreover, we elucidate the mechanism of the ferromagnetism by electron spin resonance (ESR). That is, the spins owing to ferromagnetism are strongly forced to stay in the disk plane by an anisotropy field. We conclude that spins in Ca(La)B_6 exist only within the surface layer of approximately 1.5 μm thick, and they feel strong surface magnetic anisotropy of an easy plane type.