Neutron scattering investigation of the novel itinerant-electron frustration

Stella四边形格是由两个重心相同的四面体嵌套而成的Stella四边形单元的角共享型格，是一种新型的阻挫格。在η-碳化物化合物中，磁性3d原子形成stella四边形晶格，因此，新的几何磁阻挫引起的新现象是预期的。通过磁化强度、电阻率、热导率、热膨胀、磁致伸缩和μ SR实验，研究了两种η-碳化物化合物Fe 3 Mo 3 N和Fe 6 W 6C的磁致伸缩行为，发现Fe 3 Mo 3 N具有铁磁量子临界行为和随机自旋冻结，表明铁磁有序受到几何挫挫抑制. Fe 6 W 6C的自旋冻结是由星形四边形中两个四面体的几何挫折引起的。这些结果是由Stella四边形晶格的固有挫折造成的。

The stella quadrangula lattice, which is a cornner-shared netwark of stella quadrangula units consisting of two nested tetrahedra with same center of gravity, is a novel frustrated lattice. In the eta-carbide compounds, the magnetic 3d atoms form the stella quadrangula lattice, and hence, new phenomena caused by the new geometric magnetic frustration are expected. We investigated two eta-carbide compounds, Fe3Mo3N and Fe6W6C, by means of magnetization, electrical resistivity, thermal conductivity, thermal expansion, magetostriction, and muSR experiments, and discovered intriguing phenomena.Fe3Mo3N shows a ferromagnetic quantum critical behavior as well as a random spin freezing, indicating the ferromagnetic order is suppressed by the geometric frustration. Fe6W6C shows a successive spin freezing caused by the geometric frustration originating from two tetrahedra in the stella quadrangula. These results are caused by the inherent frustration of the stella quadrangula lattice.