Nuclear Magnetic Relaxation in the Haldane-Gap Antiferromagnet Ni(C_2_H_8_N_2_)_2_NO_2_(ClO_4_)

TL;DR

This paper introduces a new theoretical approach using modified spin waves to interpret nuclear spin-lattice relaxation times in the Haldane-gap antiferromagnet NENP, addressing previously unexplained experimental observations.

Contribution

It presents the first explicit simulation of 1/T_1 relaxation times in NENP using modified spin waves, advancing understanding of spin dynamics in Haldane-gap systems.

Findings

Successfully modeled the minimum of 1/T_1 as a function of applied magnetic field.

Provided a theoretical framework that aligns with experimental relaxation data.

Bridged the gap between field-theoretical discussions and explicit simulations.

Abstract

A new theory is proposed to interpret nuclear spin-lattice relaxation-time (T_1_) measurements on the spin-1 quasi-one-dimensional Heisenberg antiferromagnet Ni(C_2_H_8_N_2_)_2_NO_2_(ClO_4_) (NENP). While Sagi and Affleck pioneeringly discussed this subject in terms of field-theoretical languages, there is no theoretical attempt yet to explicitly simulate the novel observations of 1/T_1_ reported by Fujiwara et al.. By means of modified spin waves, we solve the minimum of 1/T_1_ as a function of an applied field, pending for the past decade.