LaFeO$_3$、PrFeO$_3$、ErFeO$_3$和LuFeO$_3$的低温太赫兹光谱：准磁子共振与基态多重态跃迁
Low temperature Terahertz Spectroscopy of LaFeO$_3$, PrFeO$_3$, ErFeO$_3$, and LuFeO$_3$: Quasimagnon resonances and ground multiplet transitions
AI总结：
本研究测量了四种RFeO$_3$钙钛矿在低温和磁场下的太赫兹激发，发现其低能激发强烈依赖于镧系离子尺寸，微小晶格位移与氧离子极化率共同促成了铁电自发极化。
摘要：
我们报告了非Jahn-Teller LaFeO$_3$、PrFeO$_3$、ErFeO$_3$和LuFeO$_3$畸变钙钛矿在高达7 T外加磁场下的布里渊区中心THz激发。LaFeO$_3$的低温低能吸收在$Γ$4 (Gx, Ay, Fz)表示中显示出反铁磁和铁磁准磁子，分别位于$ω$AFM ~31.4和$ω$FM ~26.7 cm$^{-1}$。LuFeO$_3$的特征是零磁场磁共振位于$ω$AFM ~26.3 cm$^{-1}$和$ω$FM ~22.4 cm$^{-1}$，此外还有由较小Lu 4f$^{14}$引起的结构偏差触发的Fe$^{3+}$塞曼分裂晶体场(CF) 6A$_1$基态跃迁，位于~10.4 cm$^{-1}$。这种局部非中心对称偏离也存在于ErFeO$_3$（Kramers 4f$^{11}$ Er$^{3+}$ (4I15/2)；Γ2 (Fx, Cy, Gz) <TSR ~93 K)中，但~4 cm$^{-1}$的Fe$^{3+}$塞曼分裂强烈偏向高能侧。ErFeO$_3$中位于$ω$AFM ~31.5 cm$^{-1}$和$ω$FM ~21.5 cm$^{-1}$的准磁子未发生磁场诱导的能带分裂，但反铁磁($ω$AMF)/铁磁($ω$AFM)强度比增加了13倍。Fe$^{3+}$较高塞曼支与Er$^{3+}$较低塞曼支之间存在显著的场依赖CF匹配布居平衡。PrFeO$_3$中的反铁磁和铁磁共振变得宽得多，因为非Kramers Pr$^3$在A位引入配体变化，导致反铁磁模式与最低Pr$^{3+}$ CF跃迁近简并。我们得出结论，RFeO$_3$（R=稀土）的低能激发强烈依赖于镧系离子尺寸。微小晶格位移也是将畸变最严重的RFeO$_3$视为非中心对称的基础。较小稀土和非线性本征氧离子极化率引发的变化为离子与电子相互作用的交织提供了基础，从而产生铁电自发极化。
英文摘要：
We report on zone center THz excitations of non-Jahn Teller LaFeO$_3$, PrFeO$_3$, ErFeO$_3$, and LuFeO$_3$ distorted perovskites under external magnetic fields up 7 T. Low temperature-low energy absorptions of LaFeO$_3$ show antiferromagnetic and ferromagnetic quasimagnons at $ω$AFM ~31.4 and $ω$FM ~26.7 cm$^{-1}$ in the $Γ$4 (Gx, Ay, Fz) representation. LuFeO$_3$ is characterized by zero field magnetic resonances at $ω$AFM ~26.3 cm$^{-1}$ and $ω$FM ~22.4 cm$^{-1}$ in addition to Fe$^{3+}$ Zeeman-split crystal field (CF) 6A$_1$ ground transitions at ~10.4 cm$^{-1}$ triggered by structural deviations induced by smaller Lu 4f$^{14}$. This local non-centrosymmetric departure is also found in ErFeO$_3$ (Kramers 4f$^{11}$ Er$^{3+}$ (4I15/2); Γ2 (Fx, Cy, Gz) <TSR ~93 K), but with the ~4 cm$^{-1}$ Fe$^{3+}$ Zeeman branching strongly biased toward higher energies. Quasimagnons at $ω$AFM ~31.5 cm$^{-1}$ and $ω$FM ~21.5 cm$^{-1}$ in ErFeO$_3$ do not undergo field induced band splits but a 13-fold increase in the antiferro ($ω$AMF) /ferro($ω$AFM) intensity ratio. There is a remarkable field-dependent CF matching population balance between Fe$^{3+}$ higher and Er$^{3+}$ lower Zeeman branches. Antiferro- and ferro- resonances in PrFeO$_3$ turn much broader as non-Kramers Pr$^3$ introduces ligand changes at the A site leading into near degeneracy the antiferromagnetic mode and the lowest Pr$^{3+}$ CF transition. We conclude that low energy excitations in RFeO$_3$ (R=rare earth) strongly depend on the lanthanide ionic size. Minute lattice displacements also underlie considering non-centrosymmetric the most distorted RFeO$_3$ (R=rare earth). Changes triggered by the smaller rare earth and the nonlinear intrinsic oxygen ion polarizability provide grounds for interplay of ionic and electronic interactions yielding ferroelectric spontaneous polarization.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
