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Spatially modulated "Mottness" in La2-xBaxCuO4

P. Abbamonte·A. Rusydi·S. Smadici·G. D. Gu·G. A. Sawatzky·D. L. Feng
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Abstract

Stripe phases were predicted to arise in doped antiferromagnets through competition between magnetism and the kinetic energy of mobile carriers (typically holes). In copper-oxides the main experimental evidence for stripes is neutron scattering from La1.48Nd0.4Sr0.12CuO4 (LNSCO) and La1.875Ba0.125CuO4 (LBCO) which reveals coexisting static spin and charge order whose wavelengths differ by a factor of two, reminiscent of charged rivers separating regions of oppositely-phased antiferromagnetism. A neutron is an electrically neutral object, however, so does not detect charge but rather its associated lattice distortion ; it is not known if the "stripe" phase in LNSCO and LBCO actually involves ordering of the doped holes. Here we present a study of the charge order in LBCO with resonant soft x-ray scattering (RSXS). We observe giant resonances at both the mobile carrier and upper-Hubbard band features in the OK edge. These demonstrate a substantial modulation in the doped hole density as well as the amount of spectral weight near the correlated gap, i.e. the degree of "Mottness". The peak-to-trough amplitude of the valence modulation is estimated to be 0.063 holes, which if interpreted with a model of the stripe form factor suggests an integrated area of 0.59 holes under a single stripe. While only an estimate, this number agrees with what is expected for half-filled stripes.

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P. Abbamonte, A. Rusydi, S. Smadici, G. D. Gu, G. A. Sawatzky, D. L. Feng. 2005-11-01. Spatially modulated "Mottness" in La2-xBaxCuO4. https://doi.org/10.1038/nphys178

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