Magnetism of stacked multilayered graphene nanostructures in carbon microspheres

POSTER

Abstract

Morphology, structure and magnetic properties of synthesized by pyrolysis (using as precursors metal free phthalocyanine and polyethylene) samples with different concentration of nitrogen in multilayered graphene nanostructures with zigzag edges in carbon microspheres was investigated by XRD, XPS, Raman, HRTEM microscopy, magnetometry, EPR measurements. Studied magnetic characteristics depend on temperature, magnetic field and concentration of nitrogen impurity centers. Prepared sample at Tpyr=700 K demonstrates strong paramagnetism, ferromagnetism and temperature-independent diamagnetism with susceptibility $χ^{Dia}$=-10$^{-6}$ emu/gOe at T=300K. Saturation magnetization vs temperature behavior with maximum magnetization M$_s$ saturation at 20 K closely resembles a spin glass behavior. The itinerant ferromagnetism of π-electrons in narrow impurity bands is interpreted using temperature dependence of spin correlations at zigzag edges in nanographenes. A magnetic hysteresis is also observed under variation of temperature at 100$<$T$<$300 K where magnetization displays diamagnetic character.

*This work supported by Russian-Armenian (Slavonic) University from Grant #SCS15T-1C249.The work at CSULA supported by the NSF CREST Grant #HRD-1547723 and PREM programs under Grant DMR-1523588.

Presenters

  • Armen Kocharian

    • CAL State University, Los Angeles
    • Physics Department, Russian-Armenian (Slavonic) University, Yerevan

Authors

  • Armen Kocharian

    • CAL State University, Los Angeles
    • Physics Department, Russian-Armenian (Slavonic) University, Yerevan

  • Aram Manukyan

    • CAL State University, Los Angeles
    • Physics Department, Russian-Armenian (Slavonic) University, Yerevan

  • Harutyun Gyulasaryan

    • Physics, Russian-Armenian (Slavonic) University, Yerevan, Armenia
    • Physics Department, Russian-Armenian (Slavonic) University, Yerevan

  • Eduard Sharoyan

    • Laboratory of Solid State Physics, Armenia, Institute for Physical Research, NAS of Armenia
    • Institute of Physical Research, NAS of Armenia, Laboratory of Solid State Physics, Ashtarak

  • Paul Oyala

    • Division of Chemistry and Chemical Engineering,, California Institute of Technology, Pasadena
    • Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena

  • Oscar Bernal

    • CAL State University, Los Angeles
    • Physics, California State University, Los Angeles
    • Cal State Univ LA

  • Luis Valencia

    • CAL State University, Los Angeles