Volume 109, Number 1, January 2015
|Number of page(s)||6|
|Section||Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties|
|Published online||22 January 2015|
Phase separation and long-wavelength charge instabilities in spin-orbit coupled systems
1 Institut für Physik, BTU Cottbus-Senftenberg - PBox 101344, 03013 Cottbus, Germany
2 Dipartimento di Fisica Università di Roma Sapienza - Piazzale Aldo Moro 5, I-00185 Roma, Italy
3 ISC-CNR and Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, Unità di Roma Sapienza Roma, Italy
Received: 16 July 2014
Accepted: 18 December 2014
We investigate a two-dimensional electron model with Rashba spin-orbit interaction where the coupling constant $g=g(n)$ depends on the electronic density. It is shown that this dependence may drive the system unstable towards a long-wavelength charge density wave (CDW) where the associated second-order instability occurs in close vicinity to global phase separation. For very low electron densities the CDW instability is nesting-induced and the modulation follows the Fermi momentum kF. At higher density the instability criterion becomes independent of kF and the system may become unstable in a broad momentum range. Finally, upon filling the upper spin-orbit split band, finite momentum instabilities disappear in favor of phase separation alone. We discuss our results with regard to the inhomogeneous phases observed at the LaAlO3/SrTiO3 or LaTiO3/SrTiO3 interfaces.
PACS: 71.70.Ej – Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect / 73.43.Nq – Quantum phase transitions / 73.20.-r – Electron states at surfaces and interfaces
© EPLA, 2015
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