Detaching the antiferromagnetic quantum critical point from the Fermi-surface reconstruction in YbRh2Si2
Detaching the antiferromagnetic quantum critical point from the Fermi-surface reconstruction in YbRh2Si2
复制标题
DOI：
10.1038/nphys1299
复制
发表时间：
2009-07-01
期刊：
影响因子：
19.6
通讯作者：
Steglich, F.
中科院分区：
文献类型：
--
作者：
Friedemann, S.;Westerkamp, T.;Steglich, F.
由非热参数（例如压力）驱动到零温度的连续相变终止于量子临界点（QCP）。目前，重费米子系统中反铁磁QCP的理论研究主要有两种方法。传统的方法是有限温度相变的量子推广，它再现了许多情况下的物理性质（1-5）。最近的非传统模型包含了近藤效应的分解，产生了费米表面重建（6-8）-YbRh 2Si 2是这一类的原型（5，9 -11）。在YbRh_2Si_2中，反铁磁转变温度在QCP处与Kondo击穿合并。在这里，我们研究的量子临界在化学压力下的YbRh_2Si_2的演变。令人惊讶的是，对于正压，我们发现在磁有序相内的近藤击穿的签名，而负压诱导它们的分离，在扩展的范围内留下中间自旋液体型基态。这种行为表明，一个新的量子相位所产生的相互作用的近藤击穿和反铁磁QCP。
A continuous phase transition driven to zero temperature by a non-thermal parameter, such as pressure, terminates in a quantum critical point (QCP). At present, two main theoretical approaches are available for antiferromagnetic QCPs in heavy-fermion systems. The conventional one is the quantum generalization of finite-temperature phase transitions, which reproduces the physical properties in many cases(1-5). More recent unconventional models incorporate a breakdown of the Kondo effect, giving rise to a Fermi-surface reconstruction(6-8)-YbRh2Si2 is a prototype of this category(5,9-11). In YbRh2Si2, the antiferromagnetic transition temperature merges with the Kondo breakdown at the QCP. Here, we study the evolution of the quantum criticality in YbRh2Si2 under chemical pressure. Surprisingly, for positive pressure we find the signature of the Kondo breakdown within the magnetically ordered phase, whereas negative pressure induces their separation, leaving an intermediate spin-liquid-type ground state over an extended range. This behaviour suggests a new quantum phase arising from the interplay of the Kondo breakdown and the antiferromagnetic QCP.