The local spectroscopic signatures of metamagnetic criticality in Sr3Ru2O7 were explored using scanning tunneling microscopy (STM). Singular features in the tunneling spectrum were found close to the Fermi level, as would be expected in a Stoner picture of itinerant electron metamagnetism. These features showed a pronounced magnetic field dependence across the metamagnetic critical point, which cannot be understood in terms of a naive Stoner theory. In addition, a pseudo-gap structure was observed over several tens of meV, accompanied by a c(2x2) superstructure in STM images. This result represents a new electronic ordering at the surface in the absence of any measurable surface reconstruction.
Flat Bands and Enigma of Metamagnetic Quantum Critical Regime in Sr3Ru2O7
理解Sr 3Ru 2 O 7的场调谐变磁量子临界性的性质在凝聚态物理中提出了一个重大的挑战。从实验中得知，有序相内的熵形成峰值，并且出乎意料地高于外部，而磁阻率在有序相附近经历陡峭的跳跃。我们发现Sr 3Ru 2 O 7和重费米子金属之间具有挑战性的连接，表达超越微观细节的普遍物理学。我们的T-B相图的构建使我们能够解释的实验的主要特点，并明确地暗示了其非凡的低温热力学的费米子凝聚量子相变的解释，导致在有限的范围内的磁场B的平带的形成。我们发现，正是平带在QCP处产生熵峰和电阻率跳跃。
A correlated insulator at the surface of the polar metal Ca$_3$Ru$_2$O$_7$
University of St Andrews（圣安德鲁斯大学）；Diamond Light Source Ltd（钻石光源有限公司）；Max Planck Institute for Chemical Physics of Solids（马克斯·普朗克固体化学物理研究所）；National Institute for Materials Science（国立材料研究所）；MAX IV Laboratory, Lund University（隆德大学MAX IV实验室）
