Angle resolved photoemission spectroscopy study of the spin-charge separation in the strongly correlated cuprates SrCuO2 and Sr2CuO3 with S = 0 impurities

Abstract

We present the results of an Angle-Resolved Photoemission Spectroscopy study on the pristine and doped quasi-one dimensional spin chains cuprates: SrCuO2, SrCu0.99M0.01O2 with (M = Mg2+ or Zn2+), Sr2CuO3 and Sr2Cu(1-x)NixO3 with (x = 0.01 or 0.02), where the dopant is a non-magnetic impurity. Both systems are quantum critical and obey the Tomonaga-Luttinger spin liquid theory. Due to low dimensionality, the separation of the degrees of freedom of the collective excitation modes of spin and charge occurs, resulting in two distinct band dispersions ascribed to spinon and holon quasi-particles, at a binding energy of about 1.2 eV. Several experimental probes show that the finite size effect, in these strongly correlated electron compounds, resulting from chains breaking by the non-magnetic impurities, has a strong impact on the ground state of their quasi-particles excitations. On the other hand, our Angle Resolved Photoemission Spectroscopy data do not show any evolution of the spinon branch upon doping, in terms of energy position at Г. We also extract the antiferromagnetic superexchange coupling and inter-site hopping constants JAF and t.