Mesoscopic percolation network in a manganite thin film revealed by microwave impedance microscopy

ORAL

Abstract

Using a microwave impedance microscope implemented under variable temperatures and magnetic fields, we discovered a pronounced percolating network with a period of 100nm in Nd$_{0.5}$Sr$_{0.5}$MnO$_{3}$ thin films. The spatially resolved impedance maps vividly demonstrate the microscopic origin of the colossal magnetoresistance effect. Strikingly, the filamentary ferromagnetic metallic domains emergent from the antiferromagnetic charge/orbital-ordered insulating background align preferentially along certain crystal axes of the (110) SrTiO$_{3}$ substrate. Such mesoscopic glassy orders, partially smeared out by disorder effect, indicate that the substrate-induced anisotropic strain rather than the Coulomb interaction plays the dominant role in the phase separation. The microwave images also revealed drastically different domain structures between the zero-field-cool and field-cool processes, consistent with the macroscopic transport measurements.

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Authors

  • Yoshinori Tokura

    Department of Applied Physics, University of Tokyo, Tokyo Univ., RIKEN, Japan, Cross-Correlated Materials Research Group, RIKEN

  • Masashi Kawasaki

    RIKEN, Japan

  • Masao Nakamura

    RIKEN, Japan

  • Keji Lai

    Dept. Applied Physics, Stanford Univ, Stanford University, Geballe Laboratory for Advanced Materials, Stanford University

  • Worasom Kundhikanjana

    Stanford University, Geballe Laboratory for Advanced Materials, Stanford University

  • Michael Kelly

    Stanford University, Geballe Laboratory for Advanced Materials, Stanford University

  • Zhi-Xun Shen

    Stanford University, Department of Physics and SIMES, Stanford University, Dept. Applied Physics, Stanford Univ, Geballe Laboratory for Advanced Materials, Stanford University