LaCoO$_{3}$中高达600 T超高磁场下自旋三重态激子凝聚的标志

Spin state ordering of strongly correlating LaCoO$_{3}$ induced at ultrahigh magnetic fields

Magnetization measurements of LaCoO$_{3}$ have been carried out up to 133 T generated with a destructive pulse magnet at a wide temperature range from 2 to 120 K. A novel magnetic transition was found at $B>100$ T and $T>T^{*}=32\pm 5$ K which is characterized by its transition field increasing with increasing temperature. At $T<T^{*}$, the previously reported transition at $B\sim65$ T was observed. Based on the obtained $B$-$T$ phase diagram and the Clausius-Clapeyron relation, the entropy of the high-field phase at 80 K is found to be smaller for about $1.5$ J K$^{-1}$ mol$^{-1}$ than that o…

Field-induced exciton condensation in LaCoO3

Motivated by recent observation of magnetic field induced transition in LaCoO3 we study the effect of external field in systems close to instabilities towards spin-state ordering and exciton condensation. We show that, while in both cases the transition can be induced by an external field, temperature dependencies of the critical field have opposite slopes. Based on this result we argue that the experimental observations select the exciton condensation scenario. We show that such condensation is possible due to high mobility of the intermediate spin excitations. The estimated width of the corr…

Two Spin-State Crystallizations in LaCoO$_{3}$

We report a magnetostriction study of a perovskite $\rm{LaCoO}_{3}$ above 100 T using our state-of-the-art strain gauge to investigate an interplay between electron correlations and spin crossover. There has been a controversy regarding whether two novel phases in $\rm{LaCoO}_{3}$ at high magnetic fields result from crystallizations or Bose-Einstein condensation during spin crossover as manifestations of localization and delocalization in spin states, respectively. We show that both phases are crystallizations rather than condensations, and the two crystallizations are different, based on the …

High-speed 100 MHz strain monitor using fiber Bragg grating and optical filter for magnetostriction measurements under ultrahigh magnetic fields

A high-speed 100 MHz strain monitor using a fiber Bragg grating, an optical filter, and a mode-locked optical fiber laser has been devised, which has a resolution of $ΔL/L\sim10^{-4}$. The strain monitor is sufficiently fast and robust for the magnetostriction measurements of magnetic materials under ultrahigh magnetic fields generated with destructive pulse magnets, where the sweep rate is in the range of 10-100 T/$μ$s. As a working example, the magnetostriction of LaCoO$_{3}$ was measured at room temperature, 115 K, and 7$\sim$4.2 K up to a maximum magnetic field of 150 T. The smooth $B^{2}$…

关于LaCoO$_{3}$中高达600 T磁场诱导自旋交叉的综述

A review on magnetic field induced spin crossover in LaCoO$_{3}$ up to 600 T

本文综述了LaCoO$_{3}$在高达600 T高磁场下的自旋交叉现象，揭示了复杂相图与自旋态关联，并探讨了激子凝聚的可能性。

在超高压磁场下，铜氧化物绝缘体Cu2OSeO3中的五重凝聚

Quintuplet condensation in the skyrmionic insulator Cu2OSeO3 at ultrahigh magnetic fields

本研究在超高压磁场下发现铜氧化物绝缘体Cu2OSeO3中出现磁子玻色-爱因斯坦凝聚，并揭示其与磁电耦合相关的电极化特征。