Ultrafast generation of hidden phases via energy-tuned electronic photoexcitation in magnetite

• 成果类型: Article
• 署名作者: Truc, B.; Usai, P.; Pennacchio, F.; Berruto, G.; Claude, R.; Madan, I.; Sala, V.; LaGrange, T.; Vanacore, G. M.; Benhabib, S.; Carbone, F.
• 署名单位: Swiss Federal Institutes of Technology Domain; Ecole Polytechnique Federale de Lausanne; Polytechnic University of Milan; University of Milano-Bicocca; Universite Paris Saclay; Centre National de la Recherche Scientifique (CNRS)
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-12583
• DOI: 10.1073/pnas.2316438121
• 发表日期: 2024-06-25
• 关键词: insulator-metal transition; verwey transition; diffraction; fe3o4

摘要

Phase transitions occurring in nonequilibrium conditions can evolve through high -energy intermediate states inaccessible via equilibrium adiabatic conditions. Because of the subtle nature of such hidden phases, their direct observation is extremely challenging and requires simultaneous visualization of matter at subpicoseconds and subpicometer scales. Here, we show that a magnetite crystal in the vicinity of its metal-to-insulator transition evolves through different hidden states when controlled via energy-tuned ultrashort laser pulses. By directly monitoring magnetite's crystal structure with ultrafast electron diffraction, we found that upon near-infrared (800 nm) excitation, the trimeron charge/orbital ordering pattern is destroyed in favor of a phase-separated state made of cubic-metallic and monoclinic-insulating regions. On the contrary, visible light (400 nm) activates a photodoping charge transfer process that further promotes the long -range order of the trimerons by stabilizing the charge density wave fluctuations, leading to the reinforcement of the monoclinic insulating phase. Our results demonstrate that magnetite's structure can evolve through completely different metastable hidden phases that can be reached long after the initial excitation has relaxed, breaking ground for a protocol to control emergent properties of matter.