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Ultrafast orbital manipulation in transition-metal oxides

Claudio Giannetti, Universita Cattolica del Sacro Cuore, Brescia, Italy

19.06.2017 at 14:00 

The short-range interactions among the electrons occupying the copper and oxygen orbitals represent the universal underlying mechanism of many exotic properties of copper oxides, such as the intrinsic nanoscale electronic inhomogeneity, the ubiquitous antinodal pseudogap and the onset of high-temperature superconductivity. Recently, the use of ultrashort light pulses [1] has been introduced as a "non-conventional" control parameter to transiently manipulate the electronic occupation of the Cu-3d and O-2p orbitals and investigate the fundamental interactions that drive the relaxation towards the correlated ground state.
Here I will review the most recent discoveries obtained via the ultrafast manipulation of the orbital occupation in  cuprates. I will discuss the existence of a high-temperature crossover at optimal doping between the physics of a doped Mott insulator to that of a more coherent metal [2,3]. The underdoped correlated ground state constitutes the fertile ground for the onset of the low-temperature symmetry-breaking instabilities, such as the onset of charge-order.
Finally, I will address the emergence of ultrafast coherent phenomena in transition-metal oxide (TMO) heterostructures [4]. These systems can be engineered at the atomic level, thus providing the platform to investigate the transport phenomena on timescales of the order of the intrinsic decoherence time of the charge excitations. I will discuss the possible exploitation of quantum paths for the transport and collection of charge excitations in TMO-based few- monolayers devices.

1. C. Giannetti et al. Ultrafast optical spectroscopy of strongly correlated materials and high-temperature
superconductors: a non-equilibrium approach. Advances in Physics, 65:2, 58-238 (2016)
2. S. Peli et al. Mottness at finite doping and charge instabilities in cuprates. Nature Physics, AOP (2017). DOI:
3. F. Cilento et al. Antinodal collapse in superconducting copper oxides driven by charge-transfer manipulation.
arXiv:1703.03877 (2017)
4. M. Gandolfi et al. Emergent ultrafast phenomena in correlated oxides and heterostructures. Phys. Scr. 92,
034004 (2017)

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