论文标题
频段的趋势外延$ \ textit {a} $$ _ 2 $$ \ textit {b} $$ _ 2 $ o $ $ _7 $（$ \ textit {a} $ = sn，pb; $ \ textit {b}
Trends in Bandgap of Epitaxial $\textit{A}$$_2$$\textit{B}$$_2$O$_7$ ($\textit{A}$ = Sn, Pb; $\textit{B}$ = Nb, Ta) Films Fabricated by Pulsed Laser Deposition
论文作者
论文摘要
pyrochlore氧化物$ a_2b_2 $ o $ _7 $，由于晶体结构中的独特几何形状，是凝结物理物理的富有成果的游乐场。 Especially focusing on the $A$-site tetrahedral sub-lattice, in particular, pyrochlore oxides $A_2B_2$O$_7$ ($A$ = Sn, Pb and $B$ = Nb, Ta), recent theoretical studies predict the emergence of the "quasi-flat band" structure as a result of the strong hybridization between filled $A$-n$s$ and O-2$p$ orbitals.在这项工作中，我们已经建立了Sn $ _2 $ nb $ _2 $ o $ _7 $，sn $ _2 $ _2 $ _2 $ ta $ _2 $ _2 $ o $ _7 $，pb $ _2 $ _2 $ _2 $ _2 $ o $ $ _7 $，PB $ _2 $ _2 $ _2 $ _2 $ _7 $ _7 $ _7 $ _7 $ _7 $ _2 （111）底物阐明其光学特性。用于直接和间接带盖的吸收 - 边缘能量增加了sn $ _2 $ _2 $ nb $ _2 $ _2 $ o $ _7 $，sn $ _2 $ _2 $ ta $ _2 $ _2 $ o $ _7 $，pb $ _2 $ _2 $ _2 $ _2 $ _2 $ _2 $ _2 $ o _7 $ _7 $ _7 $ _7 $ _2 $ _2 $ _2 $ _2 $ _2 $ _2 $ _2可以通过考虑组成元素的能量水平来很好地解释这种趋势。直接和间接带盖之间差异的比较表明，pb $ _2b_2 $ o $ _7 $往往比sn $ _2b_2 $ o $ $ _7 $具有较小的配色价频段。我们的发现与理论预测一致，并暗示了杂交状态在这类化合物中的共同存在。
Pyrochlore oxides $A_2B_2$O$_7$ have been a fruitful playground for condensed matter physics because of the unique geometry in the crystal structure. Especially focusing on the $A$-site tetrahedral sub-lattice, in particular, pyrochlore oxides $A_2B_2$O$_7$ ($A$ = Sn, Pb and $B$ = Nb, Ta), recent theoretical studies predict the emergence of the "quasi-flat band" structure as a result of the strong hybridization between filled $A$-n$s$ and O-2$p$ orbitals. In this work, we have established the growth conditions of Sn$_2$Nb$_2$O$_7$, Sn$_2$Ta$_2$O$_7$, Pb$_2$Nb$_2$O$_7$, and Pb$_2$Ta$_2$O$_7$ films by pulsed laser deposition on Y-stabilized ZrO$_2$ (111) substrates to elucidate their optical properties. Absorption-edge energies, both for direct and indirect bandgaps, increase in the order of Sn$_2$Nb$_2$O$_7$, Sn$_2$Ta$_2$O$_7$, Pb$_2$Nb$_2$O$_7$, and Pb$_2$Ta$_2$O$_7$. This tendency can be well explained by considering the energy level of the constituent elements. A comparison of the difference between direct and indirect bandgaps reveals that Pb$_2B_2$O$_7$ tends to have a less dispersive valence band than Sn$_2B_2$O$_7$. Our findings are consistent with the theoretical predictions and are suggestive of the common existence of the hybridized states in this class of compounds.
