中文摘要：

强关联电子同时表现出局域和巡游的二重性，这是量子力学波粒二象性在凝聚态物理领域的表现，也是导致强关联材料中各种新奇量子效应的根源。本文以重费米子材料为例，探讨强关联f电子在该类材料中局域和巡游二重行为的实验表现，重点介绍重费米子的二流体唯象理论。这一理论成功解释了众多先前无法解释的实验现象，揭示了重费米子体系复杂行为背后的统一物理起源，为理解强关联系统包括铜氧化物和铁基超导材料中电子的奇异行为提供了一种新的思路，亟待更加深入的理论和实验探索。

英文摘要：

The dual （simultaneously localized and itinerant） nature of strongly correlated electrons can be traced back to the particle-wave duality in quantum mechanics and is the origin of numerous exotic quantum phenomena in correlated materials. Here we discuss the various experimental aspects of this dual behavior of f-electron and focus on the phenomenological two-fluid theory recently developed for heavy fermion materials. The two-fluid theory has been quite successful in explaining many puzzling experiments and revealing the common nature of the complex behaviors of many heavy fermion compounds. It provides a new avenue for understanding the exotic properties of strongly correlated systems including cuprates and iron-based superconductors and demands further theoretical and experimental investigations.