Spin-charge separation in single-chain compound Sr₂CuO₃ studied by angle-resolved photoemission

Angle-resolved photoemission measurements were performed for one-dimensional Sr₂CuO₃ which consists of single Cu-O chains. Two dispersive bands were observed near E_F in the first half of the Brillouin zone (k = 0 to π/2) of the chain-direction. Both bands have a common maximum point closest to E_F at k = π/2 while they show different dispersions of about 0.25 and 1 eV, respectively, with a continuous intensity distribution in between. The less dispersive band is almost diminished in another half of the Brillouin zone (k = π/2 to π). These results are consistent with the solution of the one-dimensional Hubbard model as well as the t-J model calculation, suggesting the spin-charge separation in the one-dimensional Cu-O chain. The experimental results are compared with those of the double-chain compound SrCuO₂.