Quantum Spin Ladder Compounds

Crossover from One to Two Dimensionality

Abstract

Theoretical and experimental aspects of a class of new cupric oxides called spin ladder coumpounds will be summarized, where the ladders are made from antiferromagnetic chains of S=1/2 spins by connecting them together with inter-chain antiferromagnetic bonds. Hole carriers doped into evenleg ladders have been predicted to pair, and possibly superconduct. By means of high pressure synthesis at 3-6 GPa and 1200 K, typically, two kinds of 2-leg ladder compounds SrCu₂O₃ and LaCuO_{2. 5} and a 3-leg ladder compound Sr₂Cu₃O₅ have been prepared. Their magnetic and electrical properties will be compared with theoretical predictions.