Commensurate-incommensurate crossover of charge stripe in La2-xSrxNiO4 (x ∼ 1/3) -: art. no. 196404

The temperature (T) dependence of the charge-stripe order in La2-xSrxNiO4 has been investigated in the vicinity of x similar to 1/3 by synchrotron radiation x-ray diffraction measurements. With decreasing T, a prominent commensurate-incommensurate (C-IC) crossover is observed in the x < 1/3 region, while for the x > 1/3 region the IC order is dominant over the whole T range. Such a C-IC crossover is interpreted as the entropy-driven self-doping of the charge stripes, and its x dependence indicates the clear electron-hole asymmetry with the x = 1/3 compound as the Mott insulator.