美国哥伦比亚大学Roy, Xavier团队报道了范德华金属CeSiI中的二维重费米子。相关研究成果发表在2024年1月17日出版的国际知名学术期刊《自然》。

重费米子金属是观测由电子相互作用驱动的出射量子相的原型系统。一个长期以来的愿望是降低这些材料的尺寸，以控制其量子相，但这仍然是一个重大挑战，因为传统的金属间重费米子化合物具有三维原子和电子结构。

该文中，研究人员报道了CeSiI中反铁磁有序重费米子基态的全面热力学和光谱证据，CeSiI是一种金属间化合物，包括通过弱层间范德华（vdW）相互作用结合在一起的二维（2D）金属片。由于其vdW性质，CeSiI具有准二维电子结构，研究人员可以通过剥离来控制其物理尺寸。f和传导电子在低温下相干杂化的出现得到了费米能级附近角分辨光电发射，和扫描隧道光谱的温度演化以及热容量测量的支持。对几层薄片的电输运测量揭示了重费米子行为和直至超薄区域的磁序。

该工作将CeSiI和相关材料建立为一个独特的平台，用于研究块体晶体中的尺寸受限重费米子，并使用2D器件制造技术和vdW异质结构来操纵Kondo筛选、磁序和邻近效应之间的相互作用。研究人员提供了范德华金属CeSiI中反铁磁有序重费米子基态的全面热力学和光谱证据。

附：英文原文

Title: Two-dimensional heavy fermions in the van der Waals metal CeSiI

Author: Posey, Victoria A., Turkel, Simon, Rezaee, Mehdi, Devarakonda, Aravind, Kundu, Asish K., Ong, Chin Shen, Thinel, Morgan, Chica, Daniel G., Vitalone, Rocco A., Jing, Ran, Xu, Suheng, Needell, David R., Meirzadeh, Elena, Feuer, Margalit L., Jindal, Apoorv, Cui, Xiaomeng, Valla, Tonica, Thunstrm, Patrik, Yilmaz, Turgut, Vescovo, Elio, Graf, David, Zhu, Xiaoyang, Scheie, Allen, May, Andrew F., Eriksson, Olle, Basov, D. N., Dean, Cory R., Rubio, Angel, Kim, Philip, Ziebel, Michael E., Millis, Andrew J., Pasupathy, Abhay N., Roy, Xavier

Issue&Volume: 2024-01-17

Abstract: Heavy-fermion metals are prototype systems for observing emergent quantum phases driven by electronic interactions1–6. A long-standing aspiration is the dimensional reduction of these materials to exert control over their quantum phases7–11, which remains a significant challenge because traditional intermetallic heavy-fermion compounds have three-dimensional atomic and electronic structures. Here we report comprehensive thermodynamic and spectroscopic evidence of an antiferromagnetically ordered heavy-fermion ground state in CeSiI, an intermetallic comprising two-dimensional (2D) metallic sheets held together by weak interlayer van der Waals (vdW) interactions. Owing to its vdW nature, CeSiI has a quasi-2D electronic structure, and we can control its physical dimension through exfoliation. The emergence of coherent hybridization of f and conduction electrons at low temperature is supported by the temperature evolution of angle-resolved photoemission and scanning tunnelling spectra near the Fermi level and by heat capacity measurements. Electrical transport measurements on few-layer flakes reveal heavy-fermion behaviour and magnetic order down to the ultra-thin regime. Our work establishes CeSiI and related materials as a unique platform for studying dimensionally confined heavy fermions in bulk crystals and employing 2D device fabrication techniques and vdW heterostructures12 to manipulate the interplay between Kondo screening, magnetic order and proximity effects. We present comprehensive thermodynamic and spectroscopic evidence for an antiferromagnetically ordered heavy-fermion ground state in the van der Waals metal CeSiI.

DOI: 10.1038/s41586-023-06868-x

Source: https://www.nature.com/articles/s41586-023-06868-x