High-Field Magnetization Study of the Doping Effect of Magnetic Impurity on the Organic Spin-Peierls System:p-CyDOV Radical Crystal

Abstract

The field dependence of the magnetization ( H =0- 55 T) of the mixed verdazyl radical crystals, ( p -CyDOV) 1- x ( p -CyDTV) x ( x =0, 0.01, 0.02, 0.03, 0.05, and 0.07) was measured to study the doping effect of magnetic impurity ( p -CyDTV) on the organic spin-Peierls (SP) system, 3-(4-cyanophenyl)-1,5-dimethyl-6-oxoverdazyl ( p -CyDOV) radical crystal, where the >C=O group in p -CyDOV is replaced by the >C=S group in p -CyDTV. The effect of doping on SP system is very remarkable. We have found that the high-field magnetization M ( x , H ) curves of the doped organic SP system below T SP =15.0 K can be well explained by the sum of the magnetization ( M ) of the spin-Peierls state ( C SP ( x ) M SP ( H )), one dimensional (1D) Heisenberg antiferromagnet ( C 1D-HAF ( x ) M 1D-HAF ( H )), and Curie impurity ( C Curie ( x ) M Curie ( H )), where C i ( x ) is the fraction of the i th contribution. The result suggests the coexistence of SP state and antiferromagnetic long-range order in the doped p -CyDOV radi...