Negative Colossal Magnetoresistance Driven by Carrier Type in the Ferromagnetic Mott Insulator GaV4S8

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• 作者：Etienne Janod ; Eugen Dorolti ; Benoit Corraze ; Vincent Guiot ; Sabrina Salmon ; Viorel Pop ; Fr茅d茅ric Christien ; Laurent Cario
• 刊名：Chemistry of Materials
• 出版年：2015
• 出版时间：June 23, 2015
• 年：2015
• 卷：27
• 期：12
• 页码：4398-4404
• 全文大小：492K
• ISSN：1520-5002

文摘

We report here a study on the evolution of structural and electronic properties of the lacunar spinel compounds GaV₄S₈ with charge doping. In this ferromagnetic (FM) Mott insulator, the heterovalent substitutions of Ga³⁺ by Zn²⁺ or Ge⁴⁺ allow induction of charge doping either by holes or by electrons. We show that electron-doped GaV₄S₈ displays a bulk, negative, and colossal magnetoresistance (CMR) with a relative drop of resistivity reaching 鈭?0% at 7 T in the vicinity of the Curie temperature. Conversely, hole-doped GaV₄S₈ does not display any negative CMR but a classical positive magnetoresistance. This asymmetric electron鈥揾ole doping effect challenges the common view stating that CMR effects in doped FM Mott insulators depends only on the density of carrier and not on their electron/hole nature. We show that a simple model based on multiorbital effects and Hund鈥檚 rule is able to capture the presence (absence) of negative CMR in electron- (hole-) doped GaV₄S₈.