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Hall effect in Sr14-xCuxCu24O41

We present Hall effect measurements of two-leg ladder quasi-one-dimensional copper oxides Sr14-xCaxCu24O41 (0 &#8804; x &#8804; 11.5). In these composite materials charge and spin ordering occurs within chain and ladder subsystems [1]. They have been investigated intensively during the last years due to their fascinating physical properties, especially after the discovery of superconductivity under pressure (for x > 10). They are the first superconducting copper oxides without the CuO2 planes, characteristic for high-temperature superconductors. The question of charge dynamics and hole distribution between the ladders and chains is still open, because the different experimental techniques have provided contradictory results [2-5]. Our Hall effect and electric resistivity results show typical semiconducting behavior for x < 10. We have determined the effective number of carriers and its dependence on composition (x) and temperature (T) and compared it to the number of holes in the ladders obtained by other experimental techniques [2-5]. Our results give around one carrier per formula unit for x=0, which increases slightly with x. The x=11.5 compound shows metallic behavior and our results match qualitatively Hall effect behavior found in HTC [6]. [1] T. Vuletić, et al., Phys. Rep. 428, 169 (2006). [2] T. Osafune, et al., Phys. Rev. Lett. 78, 1980 (1997). [3] N. Nücker, et al., Phys. Rev. B 62, 14384 (2000). [4] Y. Piskunov, et al., Phys. Rev. B 72, 064512 (2005). [5] A. Rusydi, et al., Phys. Rev. B 75, 104510 (2007). [6] For a review see: N. E. Hussey, J. Phys: Condens. Matter 20, 123201 (2008).

hole-doped quasi-one dimensional cuprates; spin-ladders; Hall effect

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