Developing theory of spin-change separation beyond the linear regime

• Applicant: Privatdozent Dr. Oleksandr Tsyplyatyev
• Subject Area: Theoretical Condensed Matter Physics
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 461313466

This proposal is targeted towards developing a theory of spin-charge separation beyond the linear regime. In the linear regime this phenomenon emerged from the Luttinger liquid theory as a separation of the spin of electron from its charge degree of freedom through formation of the collective modes by many interacting electrons, manifesting in two non-equal velocities for the two kinds of density modes. This effect was observed directly in semiconductor quantum wires, successfully confirming an emergent scenario of deconfinement for the fundamental properties of an electron in many-body systems. The natural progression of the experimental work is now reaching the state of providing the access to such an effect in the nonlinear regime away from the Fermi energy, demanding a theory for nonlinear spin-charge separation. However, the theoretical description of nonlinear one-dimensional systems is severely lacking at the moment since the underlying Luttinger liquid theory is broken down by any nonlinearity completely, even when it is treated as a perturbation not very far from the Fermi point. The main aim of this project is to develop a microscopic approach to calculation of the correlation functions for spin-charge separated systems in the nonlinear regime in one dimension using the available toolbox of Bethe ansatz and field-theoretical methods, which are applicable to nonlinear systems. The objectives of this proposal also include application of the newly developed microscopic technique to analysis of the spectral function and of the occupation numbers to identify the manifestations of the spin-charge separated modes away from the Fermi energy.

• DFG Programme: Research Grants
• International Connection: United Kingdom
• Cooperation Partner: Professor Dr. Christopher Ford