Possible nodal vortex state in CeRu{sub 2}
Possible nodal vortex state in CeRu{sub 2}
复制标题
CeRu{sub 2} 中可能的节点涡旋状态
DOI：
10.1103/physrevb.63.224520
复制
发表时间：
2001
影响因子：
3.7
通讯作者：
Y. Haga
中科院分区：
文献类型：
--
作者：
R. Kadono;W. Higemoto;A. Koda;K. Ohishi;T. Yokoo;J. Akimitsu;M. Hedo;Y. Inada;Y. Ōnuki;E. Yamamoto;Y. Haga
用Muon自旋旋转方法研究了高质量CeU{sub2}晶体混合态磁涡的微观性质。我们发现，介子探测到的磁感应强度B(R)的空间分布可以用三角涡旋晶格的London模型来描述，但作了适当的修正，加入了涡核周围的高场截断和低场涡旋晶格结构中长程缺陷的影响。涡核半径与H{sup({beta}{-}1)/2}成正比，其中{beta}{近似相等}为0.53(H为磁场)，这与最近观测到的电子比热系数与非线性场的关系很好地符合。特别是证实了磁穿透深度的反常增加与直流磁化强度的峰值效应(2.0K时的峰值效应)一致，这不能用常规的磁场断裂效应来解释。此外，还从微观上证明了磁通钉扎的自发增强，这也与峰值效应有关。这些结果强烈地表明，H{ge}H{sup*}具有反常增强的准粒子态密度的新的涡旋态引起集体钉扎的开始。
The microscopic property of magnetic vortices in the mixed state of a high-quality CeRu{sub 2} crystal has been studied by muon spin rotation. We have found that the spatial distribution of magnetic induction B(r) probed by muons is perfectly described by the London model for the triangular vortex lattice with appropriate modifications to incorporate the high-field cutoff around the vortex core and the effect of long-range defects in the vortex lattice structure at lower fields. The vortex core radius is proportional to H{sup ({beta}{minus}1)/2} with {beta}{approx_equal}0.53 (H being the magnetic field), which is in good agreement with the recently observed nonlinear field dependence of the electronic specific heat coefficient {gamma}{proportional_to}H{sup {beta}}. In particular, the anomalous increase of magnetic penetration depth in accordance with the peak effect in dc magnetization ({ge}H{sup *}{approx_equal}3 T at 2.0 K) has been confirmed; this cannot be explained by the conventional pair-breaking effect due to magnetic field. In addition, the spontaneous enhancement of flux pinning, which is also associated with the peak effect, has been demonstrated microscopically. These results strongly suggest the onset of collective pinning induced by a new vortex state having an anomalously enhanced quasiparticle density of states for H{ge}H{sup *}.