https://doi.org/10.1140/epjb/e2015-60044-3
Regular Article
Orbital ordering transition in the single-layer manganites near half doping: a weak-coupling approach
1 Asia Pacific Center for Theoretical
Physics, Pohang, Gyeongbuk
790-784,
Korea
2 Department of Physics, Hanyang
University, 17 Haengdang,
Seongdong, Seoul
133-791,
Korea
a
e-mail: dheeraj80@hanyang.ac.kr
Received:
14
January
2015
Received in final form:
18
February
2015
Published online:
15
April
2015
The roles of crystal-field splitting and Jahn-Teller distortions on the orbital ordering transition are investigated in the single-layer manganites near half doping. Crystal-field splitting of energy levels favoring the d3z2 − r2 occupancy provides not only the correct Fermi surface topology for La0.5Sr1.5MnO4 having a circular electron pocket around the Γ point, but also enhances the flatness of the hole pocket around the M point thereby improving the nesting. In the presence of the circular electron pocket, Jahn-Teller distortions are found to be crucial for the transition to the transverse orbital ordering with ordering wavevector (0.5π,0.5π). In the hole-doping regime 0.5 ≤ x ≤ 0.7, the orbital ordering wavevector shows a linear dependence on the hole concentration in accordance with the experiments.
Key words: Solid State and Materials
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2015