Abstract
Photo-induced hidden phases are often observed in materials with intertwined orders. Understanding the formation of these non-thermal phases is challenging and requires a resolution of the cooperative interplay between different orders on the ultra-short timescale. In this work, we demonstrate that non-equilibrium photo-excitations can induce a state with spin-orbital orders entirely different from the equilibrium state in the three-quarter-filled two-band Hubbard model. We identify a general mechanism governing the transition to the hidden state, which relies on a non-thermal partial melting of the intertwined orders mediated by photoinduced charge excitations in the presence of strong spin-orbital exchange interactions. Our study theoretically confirms the crucial role played by orbital degrees of freedom in the light-induced dynamics of strongly correlated materials and it shows that the switching to hidden states can be controlled already on the fs timescale of the electron dynamics.
Highlights
We demonstrate that in this situation, laser-induced charge excitations partially quench spin and orbital order on electronic timescales in a way that markedly differs from the effect of heating
Due to the exchange-coupling between the order parameters, this drives the system to a state that features spinorbital orders unaccessible in an equilibrium state
Starting with a near-120° AFO ordering, the photo-excited system approaches a ferro-orbital-ordering in the strong excitation limit, while an equilibrium state always reaches a 180° AFO ordering with increasing temperature
Summary
Extensive studies of the Hubbard model have provided insights into different aspects, such as charge relaxation and thermalization processes in one-band Mott insulators[18,19], the renormalization of bands by screening[20,21], and proposals for the laser control of magnetism[22,23]. While most of these studies involve single-orbital models, both strong correlations and multi-orbital degeneracy must be taken into account in order to resolve the cooperative dynamics of different orders in Mott insulators and explore the landscape of hidden states.
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