Unveiling High-Order Phonon Physics: High-Pressure Thermal Transport in Extreme Materials

High pressure provides a new dimension for exploring the transport physics and properties of materials. Over the past century, tremendous efforts have been made to study thermal transport under high pressure. However, the first-principles phonon theory for understanding thermal transport under high pressure has been rarely applied. Here, for the first time, we studied high pressure transport and identified high order anharmonic behaviors beyond the classical textbook understanding. We conducted in-situ experiments, incorporating thermal transport, vibrational spectroscopies, and synchrotron X-ray experiments. These measurements were juxtaposed with first-principles calculations, shedding light on the microscopic dynamics underlying heat transfer. Our finding uncovering high-order anharmonic behaviors beyond traditional comprehension based on classical physics. Our development enables new research platforms and provides fundamental insights into thermal transport under extreme conditions. <b>Reference:</b> <b>S. Li,</b> Z. Qin, H. Wu, M. Li, M. Kunz, A. Alatas, A. Kavner, Y. Hu, "Anomalous thermal transport under high pressure in boron arsenide," <b><i>Nature</i> 612, 459 (2022). </b>https://www.nature.com/articles/s41586-022-05381-x