论文标题
通过在Fe L边缘上共鸣的非弹性X射线散射测量的赤铁矿杂膜膜的电子激发
Electronic Excitations of Hematite Heteroepitaxial Films Measured by Resonant Inelastic X-Ray Scattering at the Fe L-edge
论文作者
论文摘要
在Fe L3边缘处测量赤铁矿的谐振非弹性X射线散射(RIX)光谱,用于在超过1 eV的能量损耗范围内未悬浮并用1%Ti,sn或Zn掺杂的杂膜薄膜,以研究电子过渡。在低温(t = 14K)和室温下进行几次动量转移(Q)测量光谱。尽管我们不能由于激发兴奋而排除分散特征,但通用光谱的粗糙信封并不能随着Q的形状而显着改变形状,这意味着大部分观察到的L边缘RIX强度来自(主要是)非散发性配体(LF)兴奋。概括Q上的RIXS光谱,并将T = 14 K的结果与T = 300 K时的结果进行比较,显示出明显的温度效应,包括1.4 eV峰的强度变化和能量移位,3-4 eV范围的宽带强度增加以及更高的能量。对于几乎所有具有不同掺杂剂的样品的样品,Q-SUMM的光谱及其温度依赖性实际上是相同的,除了Ti掺杂样品光谱的温度依赖性,我们将其归因于受大量自由电荷载体的影响。与不同温度和兴奋剂的磁化测量值进行比较,也没有显示RIXS光谱与磁有序状态之间的明显相关性。为了阐明激发态,我们执行了自旋多重计算,这些计算与RIXS光谱在广泛的能量范围内非常吻合,并提供了激发态的详细电子描述。讨论了这些发现对赤铁矿光阳极的光转换效率的影响。
Resonant Inelastic X-Ray Scattering (RIXS) spectra of hematite were measured at the Fe L3-edge for heteroepitaxial thin films which were undoped and doped with 1% Ti, Sn or Zn, in the energy loss range in excess of 1 eV to study electronic transitions. The spectra were measured for several momentum transfers (q), conducted at both low temperature (T=14K) and room temperature. While we can not rule out dispersive features possibly owing to propagating excitations, the coarse envelopes of the general spectra did not appreciably change shape with q, implying that the bulk of the observed L-edge RIXS intensity originates from (mostly) non-dispersive ligand field (LF) excitations. Summing the RIXS spectra over q and comparing the results at T=14 K to those at T=300 K, revealed pronounced temperature effects, including an intensity change and energy shift of the 1.4 eV peak, a broadband intensity increase of the 3-4 eV range, and higher energy features. The q-summed spectra and their temperature dependences are virtually identical for nearly all of the samples with different dopants, save for the temperature dependence of the Ti-doped sample's spectrum, which we attribute to being affected by a large number of free charge carriers. Comparing with magnetization measurements for different temperatures and dopings likewise did not show a clear correlation between the RIXS spectra and the magnetic ordering states. To clarify the excited states, we performed spin multiplet calculations which were in excellent agreement with the RIXS spectra over a wide energy range and provide detailed electronic descriptions of the excited states. The implications of these findings to the photoconversion efficiency of hematite photoanodes is discussed.