Abstract
Ultrafast crystal-to-liquid phase transition induced by femtosecond pulse laser excitation is an interesting material's behavior manifesting the complexity of light-matter interaction. There exist two types of such phase transitions: one occurs at a time scale shorter than a picosecond via a nonthermal process mediated by electron-hole plasma formation; the other at a longer time scale via a thermal melting process mediated by electron-phonon interaction. However, it remains unclear what material would undergo which process and why? Here, by exploiting the property of quantum electronic stress (QES) governed by quantum Hooke's law, we classify the transitions by two distinct classes of materials: the faster nonthermal process can only occur in materials like ice having an anomalous phase diagram characterized with dTm/dP < 0, where Tm is the melting temperature and P is pressure, above a high threshold laser fluence; while the slower thermal process may occur in all materials. Especially, the nonthermal transition is shown to be induced by the QES, acting like a negative internal pressure, which drives the crystal into a “super pressing” state to spontaneously transform into a higher-density liquid phase. Our findings significantly advance fundamental understanding of ultrafast crystal-to-liquid phase transitions, enabling quantitative a priori predictions.
Highlights
Ultrafast crystal-to-liquid phase transition induced by femtosecond pulse laser excitation is an interesting material’s behavior manifesting the complexity of light-matter interaction
There exist two types of such phase transitions: one occurs at a time scale shorter than a picosecond via a nonthermal process mediated by electron-hole plasma formation; the other at a longer time scale via a thermal melting process mediated by electron-phonon interaction
It remains unclear what material would undergo which process and why? Here, by exploiting the property of quantum electronic stress (QES) governed by quantum Hooke’s law, we classify the transitions by two distinct classes of materials: the faster nonthermal process can only occur in materials like ice having an anomalous phase diagram characterized with dTm/dP, 0, where Tm is the melting temperature and P is pressure, above a high threshold laser fluence; while the slower thermal process may occur in all materials
Summary
Ultrafast crystal-to-liquid phase transition induced by femtosecond pulse laser excitation is an interesting material’s behavior manifesting the complexity of light-matter interaction. The transition occurs by the QES acting like a negative internal pressure that drives the crystalline phase into a ‘‘super pressing’’ state to spontaneously transform into a higher-density liquid phase at low temperature This key identification allows us to rationalize all the known materials that exhibit the crystal-to-liquid transition under pulse laser irradiation in experiments[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21], as well as to predict unknown materials that can undergo the nonthermal melting process. Based on our theory, we can predict new materials that will exhibit nonthermal crystal-to-liquid transition for future
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