Jahn-Teller mechanism of stripe formation in doped layered La 2 - XSrxNiO4 nickelates

Marian Smoluchowski Institute of Physics, Jagellonian University, Reymonta 4, PL-30059 Kraków, Poland.
Journal of Physics Condensed Matter (Impact Factor: 2.35). 06/2011; 23(26):265601. DOI: 10.1088/0953-8984/23/26/265601
Source: arXiv


We introduce an effective model for eg electrons to describe quasi-two-dimensional layered La2 − xSrxNiO4 nickelates and study it using correlated wavefunctions on 8 × 8 and 6 × 6 clusters. The effective Hamiltonian includes the kinetic energy, on-site Coulomb interactions for eg electrons (intraorbital U and Hund's exchange JH) and the coupling between eg electrons and Jahn–Teller distortions (static modes). The experimental ground state phases with inhomogeneous charge, spin and orbital order at the dopings x = 1/3 and 1/2 are reproduced very well by the model. Although the Jahn–Teller distortions are weak, we show that they play a crucial role and stabilize the observed cooperative charge, magnetic and orbital order in the form of a diagonal stripe phase at x = 1/3 doping and a chequerboard phase at x = 1/2 doping.

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