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^{1}, S. H. Rhim

^{2}, C. J. Hirschmugl

^{2}, M. Gajdardziska-Josifovska

^{2}, M. Weinert

^{2,a)}and J. H. Chen

^{1,a)}

### Abstract

The intrinsic thermal conductivity of monolayer graphene monoxide is determined via first-principles calculations. The phonon transport in graphene monoxide is anisotropic, with the lattice thermal conductivity along the armchair direction (…C-2O-C…) about five times higher than that along the zigzag (…C-C…) direction. The predicted thermal conductivity (>3000 Wm−1K−1 at 300 K) of graphene monoxide is 80% of that of graphene along the armchair direction for large sample lateral sizes (>5 μm). In addition, heat is predominantly carried by longitudinal acoustic phonons along the armchair direction, while the contribution from the transverse acoustic phonon mode is prevalent along the zigzag direction.

The authors acknowledge the financial support from the National Science Foundation (CMMI-0856753 and CMMI-0900509), and from the Research Growth Initiative Program of the University of Wisconsin-Milwaukee (UWM).

### Key Topics

- Phonons
- 52.0
- Thermal conductivity
- 43.0
- Graphene
- 39.0
- Phonon dispersion
- 8.0
- Band gap
- 6.0

## Figures

(a) Phonon dispersion for monolayer graphene monoxide, (b) the Grüneissen parameter for acoustic phonon modes in GMO. The inset in (b) shows the unit cell of centered rectangular GMO in real space and its first Brillouin zone with the high symmetry points and lines labeled.

(a) Phonon dispersion for monolayer graphene monoxide, (b) the Grüneissen parameter for acoustic phonon modes in GMO. The inset in (b) shows the unit cell of centered rectangular GMO in real space and its first Brillouin zone with the high symmetry points and lines labeled.

Color maps of intrinsic thermal conductivities of GMO as a function of both temperature and lateral size along the XΓ direction (a) and ΓK direction (b). (c) and (d) show the thermal conductivity of GMO in (a) and (b) normalized with respect to the thermal conductivity of graphene along the MΓ direction, respectively. The lateral size starts from 2.5 μm so that the calculated thermal conductivity is diffusive, since average LA and TA phonon mean free paths for GMO are calculated as 0.48 μm and 0.13 μm along the armchair and the zigzag directions, respectively.

Color maps of intrinsic thermal conductivities of GMO as a function of both temperature and lateral size along the XΓ direction (a) and ΓK direction (b). (c) and (d) show the thermal conductivity of GMO in (a) and (b) normalized with respect to the thermal conductivity of graphene along the MΓ direction, respectively. The lateral size starts from 2.5 μm so that the calculated thermal conductivity is diffusive, since average LA and TA phonon mean free paths for GMO are calculated as 0.48 μm and 0.13 μm along the armchair and the zigzag directions, respectively.

Color maps of the ratio of thermal conductivity of LA mode to TA mode as a function of temperature and lateral size for GMO along the XΓ direction (a), GMO along the ΓK direction (b), and graphene along the MΓ direction (c), respectively.

Color maps of the ratio of thermal conductivity of LA mode to TA mode as a function of temperature and lateral size for GMO along the XΓ direction (a), GMO along the ΓK direction (b), and graphene along the MΓ direction (c), respectively.

Phonon dispersions of the ZA mode around the zone center under isotropic strains for (a) GMO and (b) graphene, respectively. (c) Grüneissen parameters of the LA and TA modes of GMO along the XΓ (upper panel) and ΓK (lower panel) directions with respect to lattice angle. (d) Thermal conductivity of GMO as a function of lattice angle at room temperature and lateral size of 5 μm along the XΓ and ΓK directions. The unstained lattice angle is 130°. Purple curves in (c) and (d) are fittings.

Phonon dispersions of the ZA mode around the zone center under isotropic strains for (a) GMO and (b) graphene, respectively. (c) Grüneissen parameters of the LA and TA modes of GMO along the XΓ (upper panel) and ΓK (lower panel) directions with respect to lattice angle. (d) Thermal conductivity of GMO as a function of lattice angle at room temperature and lateral size of 5 μm along the XΓ and ΓK directions. The unstained lattice angle is 130°. Purple curves in (c) and (d) are fittings.

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