RIKEN SPring-8 Center, RIKEN, 1-1-1 Kouto, Sayo, Hyogo, 679-5148, Japan.
International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki, 305-0047, Japan.
Sci Rep. 2017 Jul 19;7(1):5846. doi: 10.1038/s41598-017-06190-3.
A pressure-induced anomalous valence crossover without structural phase transition is observed in archetypal cubic YbCu based heavy Fermion systems. The Yb valence is found to decrease with increasing pressure, indicating a pressure-induced crossover from a localized 4f state to the valence fluctuation regime, which is not expected for Yb systems with conventional c-f hybridization. This result further highlights the remarkable singularity of the valence behavior in compressed YbCu-based compounds. The intermetallics YbPdSn, which shows two quantum critical points (QCP) under pressure and has been proposed as a potential candidate for a reentrant Yb state at high pressure, was also studied for comparison. In this compound, the Yb valence monotonically increases with pressure, disproving a scenario of a reentrant non-magnetic Yb state at the second QCP.
在典型的立方 YbCu 基重费米子体系中观察到了一种无结构相变的压力诱导异常价交叉。发现 Yb 价态随压力的增加而降低，表明从局域的 4f 态到价态涨落态的压力诱导交叉，这对于具有传统 c-f 杂化的 Yb 体系是不期望的。这一结果进一步突出了在压缩 YbCu 基化合物中价态行为的显著奇异。金属间化合物 YbPdSn 在压力下表现出两个量子临界点（QCP），并被提议作为高压下再进入 Yb 态的潜在候选者，也进行了研究以作比较。在该化合物中，Yb 价态随压力单调增加，否定了在第二个 QCP 处存在再进入非磁性 Yb 态的情况。
