Structure and magnetic properties of a La$_{0.75}$Sr$_{0.25}$Cr$_{0.90}$O$_{3-δ}$ single crystal

Kaitong Sun; Yinghao Zhu; Shinichiro Yano; Qian Zhao; Muqing Su; Guanping Xu; Ruifeng Zheng; Ying Ellie Fu; Hai-Feng Li

doi:10.1016/j.physb.2024.415776

paper

Structure and magnetic properties of a La $_{0.75}$ Sr $_{0.25}$ Cr $_{0.90}$ O $_{3 - δ}$ single crystal

arXiv:2402.08940 · doi:10.1016/j.physb.2024.415776

Abstract

We have successfully grown large and good-quality single crystals of the La $_{0.75}$ Sr $_{0.25}$ Cr $_{0.90}$ O $_{3 - δ}$ compound using the floating-zone method with laser diodes. We investigated the crystal quality, crystallography, chemical composition, magnetic properties and the oxidation state of Cr in the grown single crystals by employing a combination of techniques, including X-ray Laue and powder diffraction, scanning electron microscopy, magnetization measurements, X-ray photoelectron spectroscopy and light absorption. The La $_{0.75}$ Sr $_{0.25}$ Cr $_{0.90}$ O $_{3 - δ}$ single crystal exhibits a single-phase composition, crystallizing in a trigonal structure with the space group $R 3 ˉ c$ at room temperature. The chemical composition was determined as La $_{0.75}$ Sr $_{0.25}$ Cr $_{0.90}$ O $_{3 - δ}$ , indicating a significant chromium deficiency. Upon warming, we observed five distinctive characteristic temperatures, namely $T_{1} =$ 21.50(1) K, $T_{2} =$ 34.98(1) K, $T_{3} =$ 117.94(1) K, $T_{4} =$ 155.01(1) K, and $T_{N} =$ 271.80(1) K, revealing five distinct magnetic anomalies. Our magnetization study allows us to explore the nature of these anomalies. Remarkably, the oxidation state of chromium in the single-crystal La $_{0.75}$ Sr $_{0.25}$ Cr $_{0.90}$ O $_{3 - δ}$ , characterized by a band gap of 1.630(8) eV, is exclusively attributed to Cr $^{3 +}$ ions, making a departure from the findings of previous studies on polycrystalline materials.

24 pages, 10 figures

Structure and magnetic properties of a La0.75​Sr0.25​Cr0.90​O3−δ​ single crystal

Abstract

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Structure and magnetic properties of a La $_{0.75}$ Sr $_{0.25}$ Cr $_{0.90}$ O $_{3 - δ}$ single crystal