ESR STUDY OF DOPING EFFECTS ON THE SPIN-PEIERLS TRANSITION IN CUGEO3

The effect of doping with nonmagnetic Zn2+ ions on the spin-Peierls tr ansition in pseudo-one-dimensional CuGeO3 has been studied by ESR inte nsity and electron spin-lattice relaxation time measurements as functi ons of temperature. The results show that impurity doping in Cu0.97Zn0 .03GeO3 reduces the magnetic energy gap much more than the spin Peierl s transition temperature. Our results thus provide experimental suppor t for recent theoretical predictions that a gapless spin-Peierls state may take place in Zn+ doped CuGeO3 at intermediate doping levels in a nalogy to gapless superconductivity.