STM study of the Mn-dopants on the surface of Sr$_{3}$(Ru$_{1-x}$Mn$_{x})_{2}$O$_{7}$(x=6{\%}, 16{\%})

ORAL

Abstract

The double-layered Sr$_{3}$Ru$_{2}$O$_{7 }$is a paramagnetic metal, but the substitution of Mn for Ru (Sr$_{3}$(Ru$_{1-x}$Mn$_{x})_{2}$O$_{7})$ results in a metal-to-insulator transition at T$_{MIT}$ and antiferromagnetic (AF) ordering at T$_{M}$ (the two transitions are closely coupled for x $<$ 6{\%}). STM measurements at 4.2 K and 100 K on the surface of Sr$_{3}$(Ru$_{1-x}$Mn$_{x})_{2}$O$_{7}$ ($x$ = 6{\%}, 16{\%}) reveal a ($\surd $2 $\times \surd $2)R45$^{o}$ unit cell, consistent with the orthorhombic bulk structure. The Mn dopant has been identified through bias-dependent STM topography and dI/dV mapping. The Mn dopant equally occupies two sites which are anti-phase - one sitting at the center and the other on the corner of the ($\surd $2 $\times \surd $2)R45$^{\circ}$ unit cell. We have directly imaged the chirality of MnO$_{6}$ rotation at the anti-phase sites. In contrast to the bulk measurements, the surface is always metallic for $x $= 16{\%} and insulating only for 4.2K measurements on the $x$ = 6{\%} sample. The surface apparently suppresses the Mn-induced insulating (AF) phase observed in the bulk.

*Research at LSU is supported by NSF DMR-1002622. Research at ORNL's CNMS was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. DOE.

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Authors

  • E.W. Plummer

    • Louisiana State University
    • Louisiana State University, Baton Rouge, LA 70803, USA
    • Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803
    • Dept. of Physics, Louisiana State University, Baton Rouge, LA 70802

  • Guorong Li

    • Louisiana State University
    • Louisiana State University, Baton Rouge, LA 70803, USA

  • Qing Li

    • Oak Ridge National Laboratory
    • Center for Nanophase Materials Sciences Division, Oak Ridge National Laboratory, USA
    • Center of Nanophase Materials Sciences, Oak Ridge National Laboratory, TN, USA 37831

  • Minghu Pan

    • Oak Ridge National Laboratory
    • Center for Nanophase Materials Sciences Division, Oak Ridge National Laboratory, USA
    • Center of Nanophase Materials Sciences, Oak Ridge National Laboratory, TN, USA 37831

  • Biao Hu

    • Louisiana State University
    • Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803
    • Dept. of Physics, Louisiana State University, Baton Rouge, LA 70802

  • Von Braun Nascimento

    • Louisiana State University
    • Louisiana State University, Baton Rouge, LA 70803, USA

  • Jiandi Zhang

    • Louisiana State University
    • Louisiana State University, Baton Rouge, LA 70803, USA
    • Dept. of Physics, Louisiana State University, Baton Rouge, LA 70802

  • Rongying Jin

    • Louisiana State University
    • Louisiana State University, Baton Rouge, LA 70803, USA
    • Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803
    • Dept. of Physics, Louisiana State University, Baton Rouge, LA 70802