Intercalation and Substitution Effects of Si in Weak Itinerant Ferromagnetic Ni3Al

概要

論文の詳細を見る
The Si-intercalated compounds Ni3AlSix ($x = 0$, 0.01, 0.02, 0.05, 0.07, and 0.1) and Si substituted compounds Ni3Al1-ySiy ($ y = 0$, 0.01, 0.015, 0.02, 0.04, 0.06, 0.1, and 0.2) were synthesized and investigated by macroscopic and microscopic magnetic measurements. We found that the common features to these two systems are: (i) drastic disappearance of ferromagnetism in Ni3Al with only a small Si concentration $x_{c} \simeq 0.01$ or $y_{c} \simeq 0.02$, (ii) $T^{4/3}$-temperature dependences in both square spontaneous magnetization $M(0, T)^{2}$ and inverse initial susceptibility $\chi_{0}^{-1}$ near the Curie temperature $T_{\text{C}}$ for ferromagnetic metal. $T^{4/3}$-temperature dependence of $\chi_{0}^{-1}$ are found to hold even for the paramagnetic metals that are classified as nearly itinerant ferromagnets very close to the ferromagnetic instability. On the other hand, our 27Al NMR results show that the Si intercalation leads to the changes of the hyperfine coupling constant $A_{\text{hf}}$, the characteristic parameters of spin fluctuations, $T_{0}$ and $T_{A}$. These results indicate that the Si intercalation modify not only the density of states at the Fermi level but also the magnetic instability as well as the spin-fluctuation spectrum of Ni3Al. These results can be understood in the frame of the self-consistent renormalization (SCR) theory and the Takahashi theory of spin fluctuations.
2010-06-15