We report detailed magnetometry and high-frequency electron spin resonance (HF-ESR) measurements which allow detailed investigation on Li-Fe antisite disorder in single-crystalline $\mathrm{Li}\mathrm{Fe}\mathrm{P}{\mathrm{O}}_4$, i.e., exchange of ${\mathrm{Fe}}^{2+}$ and ${\mathrm{Li}}^{+}$ ions. The data imply that magnetic moments of ${\mathrm{Fe}}^{2+}$ ions at Li positions do not participate in long-range antiferromagnetic order in $\mathrm{Li}\mathrm{Fe}\mathrm{P}{\mathrm{O}}_4$ but form quasifree moments. Anisotropy axes of the magnetic moments at antisite defects are attached to the main crystallographic directions. The local character of these moments is confirmed by associated linear resonance branches detected by HF-ESR studies. Magnetic anisotropy shows up in significant zero-field splittings of $\mathrm{\Delta }=220\left(3\right)$ GHz, ${\mathrm{\Delta }}^{\prime }\sim 50$ GHz, and a highly anisotropic $g$ factor, i.e., $g_a=1.4, g_b=2.0$, and $g_c=6.3$. We demonstrate a general method to precisely determine Fe-antisite disorder in $\mathrm{Li}\mathrm{Fe}\mathrm{P}{\mathrm{O}}_4$ from magnetic studies which implies a density of paramagnetic ${\mathrm{Fe}}^{2+}$ ions at Li positions of 0.53%.

中文翻译：

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电池材料中的反位错

我们报告详细的磁力计和高频电子自旋共振（HF-ESR）测量，从而可以对单晶Li-Fe抗位错进行详细研究 $里铁\mathrm{P}{\mathrm{Ø}}_4$，即交换 ${铁}^{2+}$ 和 ${里}^{+}$离子。数据暗示着磁矩${铁}^{2+}$ Li位置的离子不参与长距离反铁磁顺序 $里铁\mathrm{P}{\mathrm{Ø}}_4$但形成准自由时刻 反位缺陷处的磁矩的各向异性轴连接到主晶体学方向。这些力矩的局部特征通过HF-ESR研究检测到的相关线性共振分支得到证实。磁各向异性出现在显着的零场分裂中$\mathrm{\Delta }=220（3）$ GHz， ${\mathrm{\Delta }}^{\prime }〜50$ GHz和高度各向异性 $G$ 因素，即 $G_{\mathrm{一种}}=1.4， G_b=2.0$和 $G_C=6.3$。我们展示了一种精确确定铁中铁抗体异常的通用方法$里铁\mathrm{P}{\mathrm{Ø}}_4$ 来自磁研究，这暗示着顺磁的密度 ${铁}^{2+}$ 离子在Li位置的含量为0.53％。