Ballistic low-temperature magnon heat conduction in the helimagnetic insulator Cu$_2$OSeO$_3$

ORAL

Abstract

We report on the observation of magnon thermal conductivities $\kappa_m\sim 80$~W/mK near $T=5$~K in single crystals of the helimagnetic insulator Cu$_2$OSeO$_3$, exceeding those observed previously in any other ferro- or ferrimagnet by almost two orders of magnitude. Distinguished in applied magnetic field, both magnon and phonon thermal conductivities exhibit ballistic behavior below 1K, with mean free paths limited by specimen boundaries. Changes in $\kappa_m$ through the helical-conical and conical-collinear spin-phase transitions with increasing applied field will also be discussed.

*This material is based on work supported by the U.S. DOE, Off. of BES, Div. of Mater. Sci. and Eng., under grants No. DEFG02-12ER46888 (Miami), DEFG02-08ER46544 (JHU), and the NSF, Div. of Mater. Res., Sol. St. Chem., CAREER grant No. DMR-1253562 (JHU).

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Authors

  • Narayan Prasai

    • Department of Physics, University of Miami
    • University of Miami

  • Artem Akopyan

    • University of Miami

  • Sunxiang Huang

    • University of Miami

  • Joshua L. Cohn

    • Department of Physics, University of Miami
    • University of Miami

  • Benjamin Trump

    • Johns Hopkins University

  • Guy G. Marcus

    • IQM at JHU
    • Johns Hopkins University

  • Tyrel McQueen

    • Johns Hopkins University
    • Johns Hopkins Univ
    • Johns Hopkins University, Baltimore, USA