LOW-DIMENSIONAL MAGNETIC-MATERIALS

One-dimensional (1D) magnets show novel phenomena that originate from quantum effects. In some of the 1D antiferromagnets the ground state i s a singlet and there is an energy gap to the excited state. These inc lude an antiferromagnet with a spontaneously dimerized state originati ng from a competing interaction, and spin-Peierls materials. When a sp in-Peierls system is doped with impurities, a long-range antiferromagn etic ordering appears. Spin ladders show quite different magnetic prop erties depending on the number of legs. When holes are introduced in a ladder, they can be superconductive.