Low-energy spin dynamics in the [YPc2]0 S=1/2 antiferromagnetic chain

TL;DR

This study uses 1H NMR to investigate low-energy spin dynamics in the organic antiferromagnetic chain [YPc2]0, revealing diffusive behavior and potential spin-gap presence around 1 K.

Contribution

First detailed NMR analysis of spin dynamics in [YPc2]0, demonstrating antiferromagnetic chain behavior and suggesting a possible low-temperature spin-gap.

Findings

Unpaired electron spins form an S=1/2 antiferromagnetic chain.

Spin dynamics are diffusive in nature.

Evidence of a potential spin-gap around 1 K.

Abstract

1H nuclear magnetic resonance (NMR) measurements in [YPc2]0, an organic compound formed by radicals stacking along chains, are presented. The temperature dependence of the macroscopic susceptibility, of the NMR shift and of the spin-lattice relaxation rate 1/T1 indicate that the unpaired electron spins are not delocalized but rather form a S=1/2 antiferromagnetic chain. The exchange couplings estimated from those measurements are all in quantitative agreement. The low-energy spin dynamics can be described in terms of diffusive processes and the temperature dependence of the corresponding diffusion constant suggests that a spin-gap around 1 K might be present in this compound.