Short-range Charge and Spin Superstructures in Doped Layered Co Perovskites

Date
Authors
Sakiyama, N.
Zaliznyak, I. A.
Lee, S. -H.
Mitsui, Y.
Yoshizawa, H.
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Description
We have investigated cobaltite relatives of the layered perovskite cuprates and nickelates, Pr$_{2-x}$Ca$_x$CoO$_4$ ($0.39 \leq x \leq 0.73$) and La$_{2-x}$Sr$_x$CoO$_4$ ($x = 0.61$), using elastic neutron scattering. We have discovered doping-dependent incommensurate short-range ordering of charges and magnetic moments, which in cobaltites occur in the range of heavy doping, $ 0.5 \lesssim x \lesssim 0.75$. The charge order exists already at room temperature and shows no change on cooling. The incommensurability of its propagation vector, ${\bf Q}_c = (\epsilon_c,0,l)$, roughly scales with the concentration of Co$^{2+}$ ions, $\epsilon_c \sim (1-x)$. Magnetic order is only established at low T$\lesssim 40$ K and has twice larger periodicity, indicating a dominant antiferromagnetic correlation between the nearest Co$^{2+}$ spins.
Comment: 4 pages 4 figures
Keywords
Condensed Matter - Strongly Correlated Electrons, Condensed Matter - Materials Science
Citation
Collections