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arXiv 1610.00513cond-mat.str-el
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Cs $_{3} $ C $_{60}$的A15相的Mott转变:不存在赝能隙和电荷有序

Mott transition in the A15 phase of Cs$_{3} $C$_{60}$: absence of pseudogap and charge order

H. Alloul, P. Wzietek, T. Mito, D. Pontiroli, M. Aramini, M. Riccò, J. P. Itié, E. Elkaim

摘要:

我们提出了一个详细的核磁共振研究的绝缘体到金属的转变所引起的施加压力$p$在A15相的Cs $_{3}$ C $_{60}$。我们的证据表明,绝缘反铁磁(AF)和超导(SC)相只共存于一个狭窄的$p$范围。在固定的$p$下,在SC跃迁$T_c$以上的金属态下,$^{133}$ Cs和$^{13}$ C NMR自旋晶格弛豫数据似乎受赝能隙样特征支配。我们证明,这一功能,也看到在$^{133}$ Cs NMR位移数据,而不是一个签名的莫特过渡,扩大和涂抹了逐步增加$(p,T)$。对$^{133}$ Cs NMR谱的四极分裂$ν_{Q}$的变化的分析排除了在Mott转变处的任何晶胞对称性变化,并且仅监测到晶格参数的弱变化。这些结果为从理论上考虑远超过临界点的三维多轨道系统中的莫特跃迁提供了一个机会。

英文摘要:

We present a detailed NMR study of the insulator to metal transition induced by an applied pressure $p$ in the A15 phase of Cs$_{3}$C$_{60}$. We evidence that the insulating antiferromagnetic (AF) and superconducting (SC) phases only coexist in a narrow $p$ range. At fixed $p$, in the metallic state above the SC transition $T_c$, the $^{133}$Cs and $^{13}$C NMR spin lattice relaxation data are seemingly governed by a pseudogap like feature. We prove that this feature, also seen in the $^{133}$Cs NMR shift data is rather a signature of the Mott transition, which broadens and smears out progressively for increasing $(p,T)$. The analysis of the variation of the quadrupole splitting $ν_{Q}$ of the $^{133}$Cs NMR spectrum precludes any cell symmetry change at the Mott transition and only monitors a weak variation of lattice parameter. These results open an opportunity to consider theoretically the Mott transition in a multiorbital three dimensional system well beyond its critical point.

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