Baldassarre L, Perucchi A, Mitrano M, Nicoletti D, Marini C, Pontiroli D, Mazzani M, Aramini M, Riccó M, Giovannetti G, Capone M, Lupi S
Center for Life Nano Science@Sapienza, Istituto Italiano di Tecnologia, V.le Regina Elena 291, Rome, Italy.
INSTM Udr Trieste-ST and Elettra - Sincrotrone Trieste S.C.p.A. in Area Science park, S.S. 14, km 163,5, Basovizza, Trieste, Italy.
Sci Rep. 2015 Oct 15;5:15240. doi: 10.1038/srep15240.
Cs3C60 is an antiferromagnetic insulator that under pressure (P) becomes metallic and superconducting below Tc = 38 K. The superconducting dome present in the T - P phase diagram close to a magnetic state reminds what found in superconducting cuprates and pnictides, strongly suggesting that superconductivity is not of the conventional Bardeen-Cooper-Schrieffer (BCS) type We investigate the insulator to metal transition induced by pressure in Cs3C60 by means of infrared spectroscopy supplemented by Dynamical Mean-Field Theory calculations. The insulating compound is driven towards a metallic-like behaviour, while strong correlations survive in the investigated pressure range. The metallization process is accompanied by an enhancement of the Jahn-Teller effect. This shows that electronic correlations are crucial in determining the insulating behaviour at ambient pressure and the bad metallic nature for increasing pressure. On the other hand, the relevance of the Jahn-Teller coupling in the metallic state confirms that phonon coupling survives in the presence of strong correlations.
Cs3C60是一种反铁磁绝缘体，在压力（P）作用下会变成金属，并在Tc = 38 K以下呈现超导特性。在接近磁态的T - P相图中出现的超导穹顶让人联想到在超导铜酸盐和磷化物中发现的情况，这强烈表明超导并非传统的巴丁 - 库珀 - 施里弗（BCS）类型。我们通过红外光谱并辅以动态平均场理论计算，研究了压力诱导Cs3C60中绝缘体到金属的转变。绝缘化合物被驱动向类似金属的行为转变，而在所研究的压力范围内强关联仍然存在。金属化过程伴随着 Jahn - Teller 效应的增强。这表明电子关联对于确定常压下的绝缘行为以及压力增加时的不良金属性质至关重要。另一方面，Jahn - Teller 耦合在金属态中的相关性证实了在强关联存在的情况下声子耦合仍然存在。
