Weak charge-lattice coupling requires reinterpretation of stripes of charge order in La1-xCaxMnO3

Loudon, J. C.; Cox, S.; Williams, A. J.; Attfield, J. P.; Littlewood, P. B.; Midgley, P. A.; Mathur, N. D.

Weak charge-lattice coupling requires reinterpretation of stripes of charge order in La1-xCaxMnO3

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Description

Modulations in manganites attributed to stripes of charge/orbital/spin order are thought to result from strong electron-lattice interactions that lock the superlattice and parent lattice periodicities. Surprisingly in La1-xCaxMnO3(x>0.5, 90 K), convergent beam (3.6 nm spot) electron diffraction patterns rule out charge stacking faults and indicate a superlattice with uniform periodicity. Moreover, large area electron diffraction peaks are sharper than simulations with stacking faults. Since the electron-lattice coupling does not lock the two periodicities (to yield stripes) it may be too weak to strongly localise charge.
Analysis and interpretation are improved and presented better