A “checkerboard" orbital-stripe phase and charge ordering transitions in Pr(SrxCa2 - x)Mn2O7 (0 x 0.45)Z. A. Li1, X. Li2, Z. Wang1, H. F. Tian1, C. Ma1, L. J. Zeng1 and H. X. Yang1
1 Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences Beijing 100080, China
2 Department of Communication Engineering, School of Information Engineering, University of Science and Technology Beijing 100083, China
received 5 May 2009; accepted in final form 2 June 2009; published June 2009
published online 13 July 2009
The charge/orbital ordering (COO) behaviors in the double-layered Pr(SrxCa2-x)Mn2O7 have been investigated by in situ transmission electron microscopy (TEM) observations. The experimental results reveal that two charge ordering (CO) phase transitions, so-called and , commonly exist in the orthorhombic Pr(SrxCa2-x)Mn2O7 (0 x 0.45) samples. Moreover, a “checkerboard" orbital-stripe phase characterized by two orthogonal COO modulations, and , is observed between and in all samples. Detailed TEM investigations on the x=0.2 sample, in which a visible electric polarization was found (TOKUNAGA Y. et al., Nat. Mater., 5 (2006) 937) demonstrate that the modulation only survives between and , and the “checkerboard” phase transforms into the conventional one-dimensional COO stripe phase below . The reversal of in-plane optical anisotropy across the transition (TOKUNAGA Y. et al., Nat. Mater., 5 (2006) 937) is also explained based on TEM result.
71.27.+a - Strongly correlated electron systems; heavy fermions.
71.30.+h - Metal-insulator transitions and other electronic transitions.
61.05.J- - Electron diffraction and scattering.
© EPLA 2009