Cobalt鈥揅arbon Complexes Induced Ferromagnetism in Chemically Modified Perovskite Dilute Magnetic Complex Oxides

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• 作者：Xuefeng Wang ; Bo Wan ; Kang Zhang ; Bo Zhao ; Zhaoguo Li ; Xiangang Wan ; Fengqi Song ; Bin Liu ; Xiangqian Xiu ; Yongbing Xu ; Yi Shi ; Rong Zhang
• 刊名：Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：September 5, 2013
• 年：2013
• 卷：117
• 期：35
• 页码：18258-18265
• 全文大小：494K
• 年卷期：v.117,no.35(September 5, 2013)
• ISSN：1932-7455

文摘

The clarification of ferromagnetism in dilute magnetic oxides (DMOs) is of vital importance to realize future spintronic devices. However, the mixed control of carriers, defects, and spin in most cases is inconvenient to disclose the origin of ferromagnetism in DMOs. The perovskite complex compound of (La,Sr)TiO₃ is apt to the independent control of carriers, defects, or spin through the codoping method. Here we demonstrate the combined experimental and theoretical studies on the cobalt鈥揷arbon complexes that can lead to the room-temperature ferromagnetism in perovskite chemically modified La_0.4Sr_0.6Ti_1鈥?i>xCo_xO₃ (LSTCO) samples. Such complexes are investigated by studying the dependence of magnetization on the concentrations of Co dopants and the in situ produced carbon that substitutes for some of the lattice oxygen atoms. The origin of ferromagnetism is attributed to the long-range-mediated magnetization among Co²⁺鈥揅 complexes through percolation-bound magnetic polarons, as strongly supported by the controlled experiments of thermal treatment and the structural characterization. Our density functional theoretical calculations further corroborate the important role of Co²⁺鈥揅 complexes on the induced robust ferromagnetism in LSTCO, in agreement with our experimental observations. The manipulation scheme of Co²⁺鈥揅 complexes not only provides a new understanding of the origin of ferromagnetism in DMOs but also evidences the feasibility and significance in design of other magnetic materials and spintronic devices. Moreover, the demonstrated solvothermal synthesis and postannealing method offer a facile and high-yield approach to produce high-quality transition-metal (cation) and carbon (anion) codoped DMOs to explore spintronic properties.