Effects of Uniaxial Strain on the Thermal Conductivity of Boron Arsenide

Strain engineering has emerged as a reliable approach to tailor the physicochemical properties of materials for desired performance. Cubic boron arsenide (c-BAs) is theoretically predicted to have ultrahigh thermal conductivity, making it a highly promising candidate for thermal management in high-power-density devices. However, the effect of uniaxial strain on its thermal transport properties remains unclear, limiting a comprehensive understanding of its practical performance. In this work, we explore the lattice thermal transport in c-BAs under uniaxial strain by combining first-principles calculations with the phonon Boltzmann transport equation. We find that the lattice thermal conductivity (κ_L) of c-BAs exhibits a nonmonotonic dependence on uniaxial strain, with an overall decreasing trend under both tensile and compressive strain. Under tension, κ_L decreases steadily due to enhanced four-phonon (4ph) scattering, resulting in a 32% reduction at +8% strain. In contrast, compression causes a brief increase in κ_L owing to suppressed 4ph scattering, followed by a sustained decrease as three-phonon (3ph) scattering becomes dominant. This behavior is attributed to the competing effects of 3ph and 4ph scattering, as well as strain-induced renormalization in acoustic phonon group velocities and lifetimes, which further shape the κ_L response. We quantitatively explain the strain-dependent thermal conductivity of c-BAs and offer deeper insights into how uniaxial strain influences its phonon transport properties. Therefore, our work bridges the gap in understanding the characteristics of c-BAs under strain, providing theoretical support for its future applications.