论文标题
Jahn-Teller Active Fluoroperovskites $ a \ Mathrm {Crf_3} $ $ a = \ Mathrm {Na^+}，\ Mathrm {K^+} $：Thermo-和Magneto Optical相关性作为$ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a-se
The Jahn-Teller active fluoroperovskites $A\mathrm{CrF_3}$ $A=\mathrm{Na^+},\mathrm{K^+}$: thermo- and magneto optical correlations as function of the $A$-site
论文作者
论文摘要
铬（ii）氟Properovskites $ a \ mathrm {crf_3}（a \ mathrm {= na^+，k^+}）$在低温下密切相关的jahn-teller活性材料。在本文中，我们研究了$ site离子使用实验方法（XRD，光学吸收光谱和磁场）和DFT模拟的作用。与温度相关的光学吸收实验表明，自旋允许的过渡$ e_2 $和$ e_3 $仅在2 k处完全合并为$ a $ = na。在2 k时，符合场依赖的光学吸收测量表明，$ \ \ \ \ \ \ \ \ \ \ naCrmf_3} $增加的旋转强度的振动强度与增加了$ \ nacrm {naCrf_3} $增加。在其Neél温度以下的$ {\ rm kcrf_3} $中观察到抑制自旋叉过渡的直接磁结构相关性。在$ {\ rm nacrf_3} $中，自旋叉过渡突然消失了9 k以下9 k，揭示了与晶体结构变化无关的磁光相关性。这表明，由于远距离排序减少了单个$ {\ rm crf_6^{4 - }} $ contahedra的本地JT效应，以控制观察到的行为。我们的结果表明，与IsoelectRonic $ a_x {\ rm Mnf} _ {3+X} $ System的模式明显偏差。 $ a $ site阳离子的大小在指示物理属性和相变为$ a {\ rm crf} _3 $中是核心的，开放了改变构图以创建具有可调属性新颖的物质状态的可能性。
Chromium (II) fluoroperovskites $A\mathrm{CrF_3}(A\mathrm{=Na^+,K^+})$ are strongly correlated Jahn-Teller active materials at low temperatures. In this paper, we examine the role that the $A$-site ion plays in this family of fluoroperovskites using both experimental methods (XRD, optical absorption spectroscopy and magnetic fields) and DFT simulations. Temperature-dependent optical absorption experiments show that the spin-allowed transitions $E_2$ and $E_3$ only merge completely for $A$= Na at 2 K. Field-dependent optical absorption measurements at 2 K show that the oscillating strength of the spin-allowed transitions in $\mathrm{NaCrF_3}$ increases with increasing applied field. Direct magneto-structural correlations which suppress the spin-flip transitions are observed for ${\rm KCrF_3}$ below its Neél temperature. In ${\rm NaCrF_3}$ the spin-flip transitions vanish abruptly below 9 K revealing magneto-optical correlations not linked to crystal structure changes. This suggests that as the long range ordering is reduced local JT effects in the individual ${\rm CrF_6^{4-}}$ octahedra take control of the observed behavior. Our results show clear deviation from the pattern found for the isoelectronic $A_x{\rm MnF}_{3+x}$ system. The size of the $A$-site cation is shown to be central in dictating the physical properties and phase transitions in $A{\rm CrF}_3$, opening up the possibility of varying the composition to create novel states of matter with tuneable properties.
