ELECTRONIC AND MAGNETIC PROPERTIES OF CUPRATE CHAINS AND RELATED MATERIALS From bandstructure to aspects of many-body physics in real materials

摘要

Band structure calculations for CuO_3 and CuO_2 chain compounds as well as for zigzag Cu_2O_4 double chain compounds are reported. These cuprate chains form the basic elements of a rich and beautiful variety of cuprate structures. From the dispersion of the antibonding band crossing the Fermi energy the exchange interaction is estimated and qualitative trends in the antiferromagnetic ordering at low temperatures are well explained. From the comparison of exact diagonalization studies of corresponding periodic chains with frequently used approximations a restricted validity of the latter with respect to the hole doping amount is found. The possibility of CDW-BOW states is discussed on the basis of self-consistent adiabatic studies. Chain aspects for superconductivity and the possible relationship to the stripe scenario are briefly discussed.