Direct Observation of a Uniaxial Stress-driven Lifshitz Transition in Sr$_{2}$RuO$_{4}$
V. Sunko, E. Abarca Morales, I. Marković, M. E. Barber, D. Milosavljević, F. Mazzola, D. A. Sokolov, N. Kikugawa, C. Cacho, P. Dudin, H. Rosner, C. W. Hicks, P.… 展开作者
V. Sunko, E. Abarca Morales, I. Marković, M. E. Barber, D. Milosavljević, F. Mazzola, D. A. Sokolov, N. Kikugawa, C. Cacho, P. Dudin, H. Rosner, C. W. Hicks, P. D. C. King, A. P. Mackenzie
Pressure represents a clean tuning parameter for traversing the complex phase diagrams of interacting electron systems and as such has proved of key importance in the study of quantum materials. Application of controlled uniaxial pressure has recently been shown to more than double the transition temperature of the unconventional superconductor Sr$_{2}$RuO$_{4}$ for example, leading to a pronounced peak in $T_\mathrm{c}$ vs. strain whose origin is still under active debate. Here, we develop a simple and compact method to apply large uniaxial pressures passively in restricted sample environments, and utilize this to study the evolution of the electronic structure of Sr$_{2}$RuO$_{4}$ using angle-resolved photoemission. We directly visualize how uniaxial stress drives a Lifshitz transition of the $γ$-band Fermi surface, pointing to the key role of strain-tuning its associated van Hove singularity to the Fermi level in mediating the peak in $T_\mathrm{c}$. Our measurements provide stringent constraints for theoretical models of the strain-tuned electronic structure evolution of Sr$_{2}$RuO$_{4}$. More generally, our novel experimental approach opens the door to future studies of strain-tuned phase transitions not only using photoemission, but also other experimental techniques where large pressure cells or piezoelectric-based devices may be difficult to implement.
Quantum Oscillations of $\mathrm{Sr}_2\mathrm{RuO}_4$ under c-Axis Uniaxial Stress
Max Planck Institute for Chemical Physics of Solids（马克斯·普朗克固体化学物理研究所）；Scottish Universities Physics Alliance (SUPA), School of Physics and Astronomy, University of St Andrews（圣安德鲁斯大学物理与天文学学院苏格兰大学物理联盟）；National Institute for Materials Science（国立材料研究所）；Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology（卡尔斯鲁厄理工学院量子材料与技术研究所）
Entropy mapping under uniaxial pressure utilizing the elastocaloric effect
Max Planck Institute for Chemical Physics of Solids（马克斯·普朗克固体化学物理研究所）；Scottish Universities Physics Alliance, School of Physics and Astronomy, University of St Andrews（圣安德鲁斯大学物理与天文学学院苏格兰大学物理联盟）；Department of Physics, National Taiwan University（台湾大学物理学系）；National Institute for Materials Science（国立材料研究所）
Magnetic structures and reorientation transitions in noncentrosymmetric uniaxial antiferromagnets
本文发展了一个非中心对称四元反铁磁体磁态的唯象理论，该理论必须包括由Dzyaloshinskiii-Moriya耦合导出的均匀项和非均匀项（Lifshitz不变量）。这类具有低晶体对称性的反铁磁体的磁性进行了讨论，其第一个已知的成员，最近检测到的化合物Ba 2CuGe 2 O 7和K2 V3 O 8。这些系统中的晶体对称性和磁有序性允许同时发生手性不均匀磁结构和弱铁磁性。新类型的无公度磁结构是可能的，即手性螺旋与旋转的交错磁化和振荡的总磁化。研究了场致重取向到调制态的转变，并绘制了相应的相图。讨论了磁缺陷的结构（畴壁和涡旋）。特别是，涡旋，即本地化的非奇异线缺陷，是稳定的单轴非中心对称反铁磁体的非均匀Dzyaloshinskiii-Moriya相互作用。
