Intervalence charge transfer and charge transport in the spinel ferrite ferromagnetic semiconductor Ru-doped CoFe2O4
Intervalence charge transfer and charge transport in the spinel ferrite ferromagnetic semiconductor Ru-doped CoFe2O4
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尖晶石铁氧体铁磁半导体Ru掺杂CoFe2O4中的层间电荷转移和电荷输运
DOI：
10.1103/physrevb.105.205103
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
and Hitoshi Tabata
中科院分区：
文献类型：
--
作者：
Masaki Kobayashi;Munetoshi Seki;Masahiro Suzuki;Ryo Okano;Miho Kitamura;Koji Horiba;Hiroshi Kumigashira;Atsushi Fujimori;Masaaki Tanaka;and Hitoshi Tabata
价间电荷转移（IVCT）是指电子通过桥接配体在两个具有不同氧化态的金属位点之间进行转移。我们认为，IVCT与固体中电子的跳跃概率（或电子迁移率）有关。控制铁磁半导体（FMSs）的电导率对于器件应用至关重要，因此，通过IVCT操纵电导率可能是FMSs波段工程的一种方法。在具有铁磁性和半导体输运性质的Ru掺杂（CFO）中，电阻率的降低是由于Ru取代Co引起的载流子掺杂和宽的Ru轨道和fe2轨道之间的杂化引起的载流子迁移率的增加。后者表示所谓的IVCT机制，即混合价态之间的电荷转移，由桥接Ruorbital促进，表示为。为了阐明IVCT状态的出现，我们对未掺杂的CFO和钌掺杂（CRFO）薄膜进行了x射线吸收光谱（XAS）和谐振光发射光谱（RPES）测量。XAS和RPES光谱分析表明，稀土和稀土之间存在混合价态和杂化。这些结果为CRFO中的IVCT态提供了实验证据，证明了通过具有干预态的过渡金属阳离子之间的杂化来控制电子迁移的机制。
Intervalence charge transfer (IVCT) refers to the transfer of electrons between two metal () sites with different oxidation states, through a bridging ligand:. It is considered that the IVCT is related to the hopping probability of electrons (or electron mobility) in solids. Controlling the conductivity of ferromagnetic semiconductors (FMSs) is critical for device applications, and thus, the manipulation of conductivity through IVCT may be an approach of band engineering in FMSs. In Ru-doped(CFO), which shows ferrimagnetism and semiconducting transport properties, the reduction in electric resistivity is attributed to both carrier doping caused by the Ru substitution of Co and increase in carrier mobility due to hybridization between the wide Ruand Feorbitals. The latter indicates the so-called IVCT mechanism, i.e., charge transfer between the mixed valencestates, facilitated by the bridging Ruorbital, expressed as. To elucidate the emergence of the IVCT state, we conducted x-ray absorption spectroscopy (XAS) and resonant photoemission spectroscopy (RPES) measurements on undoped CFO and Ru-doped(CRFO) thin films. The XAS and RPES spectra indicated the presence of mixed valencestates and hybridization between the Feand Rustates. These results provide experimental evidence for the IVCT state in CRFO, demonstrating a mechanism that controls electron mobility through hybridization between thetransition metal cations with interveningstates.