Ronchi Andrea, Franceschini Paolo, De Poli Andrea, Homm Pía, Fitzpatrick Ann, Maccherozzi Francesco, Ferrini Gabriele, Banfi Francesco, Dhesi Sarnjeet S, Menghini Mariela, Fabrizio Michele, Locquet Jean-Pierre, Giannetti Claudio
Department of Mathematics and Physics, Università Cattolica del Sacro Cuore, Brescia, I-25133, Italy.
Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, 3001, Leuven, Belgium.
Nat Commun. 2022 Jun 28;13(1):3730. doi: 10.1038/s41467-022-31298-0.
Mott transitions in real materials are first order and almost always associated with lattice distortions, both features promoting the emergence of nanotextured phases. This nanoscale self-organization creates spatially inhomogeneous regions, which can host and protect transient non-thermal electronic and lattice states triggered by light excitation. Here, we combine time-resolved X-ray microscopy with a Landau-Ginzburg functional approach for calculating the strain and electronic real-space configurations. We investigate VO, the archetypal Mott insulator in which nanoscale self-organization already exists in the low-temperature monoclinic phase and strongly affects the transition towards the high-temperature corundum metallic phase. Our joint experimental-theoretical approach uncovers a remarkable out-of-equilibrium phenomenon: the photo-induced stabilisation of the long sought monoclinic metal phase, which is absent at equilibrium and in homogeneous materials, but emerges as a metastable state solely when light excitation is combined with the underlying nanotexture of the monoclinic lattice.
真实材料中的莫特转变是一级相变，并且几乎总是与晶格畸变相关联，这两个特征都促进了纳米织构相的出现。这种纳米级的自组织产生了空间上不均匀的区域，这些区域可以容纳和保护由光激发触发的瞬态非热电子态和晶格态。在这里，我们将时间分辨X射线显微镜与朗道-金兹堡泛函方法相结合，以计算应变和电子实空间构型。我们研究了VO，这是一种典型的莫特绝缘体，其中纳米级自组织在低温单斜相中已经存在，并强烈影响向高温刚玉金属相的转变。我们的联合实验-理论方法揭示了一种显著的非平衡现象：长期以来寻找的单斜金属相的光致稳定化，该相在平衡态和均匀材料中不存在，但仅当光激发与单斜晶格的潜在纳米织构相结合时才作为亚稳态出现。
