Spin dynamics and antiferromagnetic order in PrBa2Cu4O8 studied by Cu nuclear respnance

TL;DR

This study uses nuclear resonance techniques to investigate the magnetic order and spin dynamics in PrBa2Cu4O8, revealing antiferromagnetic order in Cu sites and clarifying the material's conduction mechanism.

Contribution

It provides direct evidence of antiferromagnetic order in the Cu sites of PrBa2Cu4O8 using NMR and NQR, and explains spin-lattice relaxation rates with a Heisenberg model.

Findings

Internal magnetic field of 6.1 T at 1.5 K indicating antiferromagnetic order

CuO2 planes are insulating, conduction occurs in Cu2O2 chains

Spin-lattice relaxation rates align with Heisenberg model predictions

Abstract

Results of the nuclear resonance experiments for the planar Cu sites in PrBa2Cu4O8 are presented. The NMR spectrum at 1.5 K in zero magnetic field revealed an internal field of 6.1 T, providing evidence for an antiferromagnetic order of the planar Cu spins. This confirms that the CuO2 planes are insulating, therefore, the metallic conduction in this material is entirely due to the one-dimensional zigzag Cu2O2 chains. The results of the spin-lattice relaxation rates measured by zero field NQR above 245 K in the paramagnetic state are explained by the theory for a Heisenberg model on a square lattice.