The valence state of Ce in a canonical heavy fermion compound CeRu2Si2 has been investigated by synchrotron X-ray absorption spectroscopy at 1.8 K in high magnetic fields of up to 40 T. The valence was slightly larger than for the pure trivalent state (Ce3+: f1), as expected in heavy fermion compounds, and it decreased toward the trivalent state as the magnetic field was increased. The field-induced valence reduction indicates that the itinerant character of the 4f electrons in CeRu2Si2 was suppressed by a strong magnetic field. The suppression was gradual and showed characteristic magnetic field dependence, which reflects the metamagnetism around Hm \sim 8 T. The itinerant character persisted, even at 40 T (\sim 5Hm), suggesting that the Kondo bound state is continuously broken by magnetic fields and that it should completely collapse at fields exceeding 200 T.
Strong competition between orbital-ordering and itinerancy in a frustrated spinel vanadate
在凝聚态物理中，从定域电子行为到巡游电子行为的转换与许多有趣的现象有关。本文研究了尖晶石系统Mn $_{1-x}$ Co $_x$ V $_2$ O $_4$从定域到巡游态的过渡。在低Co掺杂下，V3+离子上的局域电子的轨道顺序（OO）通过触发四重态畸变来抑制磁挫挫。随着Co掺杂，电子巡回熔化OO和抑制结构相变，而减少的自旋-晶格耦合产生磁阻挫。中子散射测量和第一性原理指导的自旋模型表明，在高Co掺杂的非共线态是由削弱的局部各向异性和增强的Co-V自旋相互作用。
Possible co-existence of local itinerancy and global localization in a quasi-one-dimensional conductor
在链状化合物PrBa $_2$ Cu $_4$ O $_8$中，当链中的散射速率超过链间的跳跃速率时，局域化与电子基态中的空间交叉同时出现.在这里，我们报告了一个大的发现，横向磁阻PrBa $_2$ Cu $_4$ O $_8$在本地化制度。这一结果表明，一种新的形式的本地化，使电子保留其金属（准一维）字符在微观长度尺度上，尽管事实上，宏观上，他们表现出本地化（一维）的行为。
Orbital order and electron itinerancy in CoV$_{2}$O$_{4}$ and Mn$ _{0.5} $Co$ _{0.5} $V$_{2}$O$_{4}$ from first principles
鉴于最近的实验预测的一个弱的结构转变的CoV $_{2}$ O $_{4}$，我们探讨了可能的轨道顺序状态，在其低温四电子相的第一性原理密度泛函理论计算。我们观察到，与I4 $_1/amd$对称性的tetraphite相关联的轨道顺序涉及复杂的轨道与一个合理的大的轨道矩在Vanessa网站，而在与I4 $_1/a$对称性的阶段，实轨道与淬灭的轨道矩构成的轨道顺序。此外，为了研究轨道有序和电子巡回之间的竞争，我们认为Mn $_{0.5}$ Co $_{0.5}$ V $_{2}$ O $_{4}$是母体化合物之一，CoV $_{2}$ O $_{4}$位于巡回极限附近，而另一个Mn V $_{2}$ O $_{4}$位于轨道有序绝缘区的深处。用第一性原理密度泛函理论和Boltzmann输运理论研究了CoV $_{2}$ O $_{4}$、MnV $_{2}$ O $_{4}$和Mn $_{0.5}$ Co $_{0.5}$ V $_{2}$ O $_{4}$的轨道有序和电子输运.我们的结果表明，当我们从MnV $_{2}$ O $_{4}$到CoV $_{2}$ O $_{4}$时，电子的巡回性增强，而轨道顺序的性质保持不变。
Near itinerancy and slow singlet formation in the triangular lattice NaRuO2
University of California Santa Barbara（加州大学圣塔芭芭拉分校）；Leibniz IFW Dresden（莱布尼茨德累斯顿研究所）；Argonne National Laboratory（阿贡国家实验室）；Helmholtz-Zentrum Dresden-Rossendorf（德累斯顿-罗斯多夫亥姆霍兹中心）；Deutsches Elektronen-Synchrotron DESY（德国电子同步加速器研究中心）
Anisotropic suppression of quasiparticle weight in two-dimensional electron system with partially flat Fermi surface: two-loop renormalization-group analysis
本文对具有部分平坦费米面的二维电子系统进行了双圈重整化群分析。我们发现，{ \it不考虑配对机制}，准粒子的重量是各向异性抑制由于在费米面的平坦区域的几何奇异过程。当能量标度减小时，准粒子重量在平坦区域的中心附近受到最强烈的抑制，这定性地同意通过角度分辨光电子能谱实验对欠掺杂Bi $_2$ Sr $_2$ CaCu $_2$ O $_8$提出的各向异性赝能隙行为。
The evolution of pairing correlation with $3d_{z^{2}}$ electron filling in a bilayer two-orbital model for La$_3$Ni$_2$O$_7$
Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University（上海交通大学物理与天文学院人工结构与量子控制教育部重点实验室）；State Key Laboratory of Quantum Functional Materials, School of Physical Science and Technology, ShanghaiTech University（上海科技大学物理科学与技术学院量子功能材料国家重点实验室）；Tsung-Dao Lee Institute, Shanghai Jiao Tong University（上海交通大学李政道研究所）；Hefei National Laboratory（合肥国家实验室）
Disorder Suppression of Charge Density Waves in the Honeycomb Holstein Model
School of Physical Science and Technology, Beijing University of Posts and Telecommunications（北京邮电大学物理科学与技术学院）；School of Physics and Astronomy, Beijing Normal University（北京师范大学物理与天文学院）；Key Laboratory of Multiscale Spin Physics (Ministry of Education), Beijing Normal University（北京师范大学多尺度自旋物理教育部重点实验室）
