Defects Vibrations Engineering for Enhancing Interfacial Thermal Transport

To push upper boundaries of effective thermal conductivity in polymer composites, a fundamental understanding of thermal transport mechanisms is crucial. Although there is intensive simulation research, systematic experimental investigation on thermal transport in polymer composites is limited. To better understand thermal transport processes, we design polymer composites with perfect fillers (graphite) and defective fillers (graphite oxide); we choose polar polyvinyl alcohol (PVA) as a matrix model; and we identify how thermal transport occurs across heterogeneous interfaces. Measured thermal conductivities of in PVA/defective filler composites is higher than those of PVA/perfect filler composites, while measured thermal conductivities in defective fillers are lower than those of perfect fillers. An effective quantum mechanical model is developed, showing that the vibrational state of the defective level plays a critical role in enhancing the thermal conductivity with increased defect concentration. Our experimental and model results have suggested that defects in polymer composites may enhance thermal transport in polymer composites by promoting vibrational resonant couplings.Comment: Enclosed: (i) Main Manuscript, including 5 main figures. (ii) Supplementary Information, including 16 Supplementary Figures and one self-contained theoretical sectio

Current-induced switching of a van der Waals ferromagnet at room temperature

Abstract Recent discovery of emergent magnetism in van der Waals magnetic materials (vdWMM) has broadened the material space for developing spintronic devices for energy-efficient computation. While there has been appreciable progress in vdWMM discovery, a solution for non-volatile, deterministic switching of vdWMMs at room temperature has been missing, limiting the prospects of their adoption into commercial spintronic devices. Here, we report the first demonstration of current-controlled non-volatile, deterministic magnetization switching in a vdW magnetic material at room temperature. We have achieved spin-orbit torque (SOT) switching of the PMA vdW ferromagnet Fe3GaTe2 using a Pt spin-Hall layer up to 320 K, with a threshold switching current density as low as $${J}_{{{{{{\rm{sw}}}}}}}=$$ J sw = 1.69 $$\times$$ × 106 A cm−2 at room temperature. We have also quantitatively estimated the anti-damping-like SOT efficiency of our Fe3GaTe2/Pt bilayer system to be $${\xi }_{{{{{{\rm{DL}}}}}}}=0.093$$ ξ DL = 0.093 , using the second harmonic Hall voltage measurement technique. These results mark a crucial step in making vdW magnetic materials a viable choice for the development of scalable, energy-efficient spintronic devices