\lco{} is known for its two-step spin crossover as a function of temperature. Despite efforts spanning over half a century, the origin of this phenomenon is still debated, particularly regarding how the microscopic spin states are involved in the observed macroscopic two-step spin crossover. High magnetic field studies on LaCoO$_{3}$ are performed because the magnetic field-induced spin crossover is induced, where the magnetic excited states become more stable in high magnetic fields than the non-magnetic ground states. This review focuses on the findings in LaCoO$_{3}$ at high magnetic fields over the last decade. A complex phase diagram has been revealed at high magnetic fields instead of solving the conventional problem of LaCoO$_{3}$. It suggests that appreciable spin state correlations are in play in LaCoO$_{3}$. The possibility of exciton condensation is also discussed.
Investigation of the Electronic Structure and Spin-State Crossover in LaCoO3 Using Photoemission Spectroscopy
Institute of Physics（印度物理研究所）；Homi Bhabha National Institute（霍米·巴巴国立研究所）；Institute for Solid State Physics, The University of Tokyo（东京大学固体物理研究所）；Deutsches Elektronen-Synchrotron DESY（德国电子同步加速器中心）
Magnetic-field-induced spin crossover of Y-doped Pr$_{0.7}$Ca$_{0.3}$CoO$_{3}$
最近发现空穴掺杂的Pr基钙钛矿钴酸盐Pr $_{0.5}$ Ca $_{0.5}$ CoO $_{3}$和（Pr $_{1-y}$ RE $_{y}$）$_{0.3}$ Ca $_{0.7}$ CoO $_{3}$（其中RE是稀土）的家族表现出同时的金属-绝缘体、自旋态和价态转变。我们研究了磁场诱导的相变（Pr $_{1-y}$ Y $_{y}$）$_{0.7}$钙$_{0.3}$ CoO $_{3}$的磁化强度测量在4.2 $-$ 100 K的140 T的磁场与$y$ = 0.0625，0.075，0.1变化的化学压力。所观察到的磁场诱导的转变被发现同时发生的金属-绝缘体转变高达100 T。用单离子自旋交叉模型分析了所得到的磁场-温度（$B$-$T$）相图和磁化曲线。另一方面，化学压力依赖性的实验获得的磁化强度变化在相变过程中不同意与单离子模型接近低温时。在低温下的磁化强度变化的显着$y$依赖性可能是由于在顺磁金属相中Co $^{3+}$的巡回磁性，其中化学压力通过促进双交换相互作用增强了交换分裂。所观察到的（Pr $_{1-y}$ Y $_{y}$）$_{0.7}$ Ca $_{0.3}$ CoO $_{3}$的$B$-$T$相图与LaCoO $_{3}$的$B$-$T$相图完全相反，表明在（Pr $_{1-y}$ Y $_{y}$）$_{0.7}$ Ca $_{0.3}$ C…
Phonons reflect dynamic spin-state order in LaCoO$_3$
Karlsruhe Institute of Technology（卡尔斯鲁厄理工学院）；RIKEN（理化学研究所）；SPring-8/JASRI（SPring-8/日本同步辐射研究所）；Physikalisches Institut, Karlsruhe Institute of Technology（卡尔斯鲁厄理工学院物理研究所）；Karlsruhe Nano Micro Facility (KNMFi), Karlsruhe Institute of Technology（卡尔斯鲁厄纳米微设施，卡尔斯鲁厄理工学院）；Laboratoire Léon Brillouin (CEA-CNRS)（莱昂·布里渊实验室）；Institut Laue-Langevin（朗之万研究所）；Argonne National Laboratory（阿贡国家实验室）；Jülich Centre for Neutron Science (JCNS), Forschungszentrum Jülich GmbH（于利希中子科学中心）；Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München（海因茨·迈尔-莱布尼茨中心，慕尼黑工业大学）
100 MHz high-speed strain monitor using fiber Bragg grating and optical filter applied for magnetostriction measurements of cobaltite at magnetic fields beyond 100 T
