Quasi-One-Dimensional Spin Excitations in the Iron Pnictide NaFe_{0.53}Cu_{0.47}As

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Magnetism

Background:

• Understanding low-dimensional quantum materials is crucial for developing novel electronic devices.
• Two-dimensional (2D) superconductors like cuprates and iron pnictides are technologically significant but complex.
• Identifying and characterizing model systems with predominantly one-dimensional (1D) physics is essential for comparative studies.

Purpose of the Study:

• To investigate the magnetic excitations in NaFe_{0.53}Cu_{0.47}As single crystals.
• To determine the dimensionality of spin excitations in this material.
• To explore the role of atomic ordering and magnetic dilution in controlling magnetic dimensionality.

Main Methods:

• Inelastic neutron scattering (INS) measurements were performed on NaFe_{0.53}Cu_{0.47}As single crystals.
• Analysis of spin excitation spectra to identify dominant exchange interactions and dimensionality.
• Comparison of spin excitation properties with related quasi-2D materials like FeSe.

Main Results:

• Direct evidence of quasi-1D spin excitations was observed, attributed to alternating magnetic Fe and nonmagnetic Cu chains.
• The dominant antiferromagnetic exchange interaction along the chain (SJ_{∥}≈90.1 meV) was quantified, with significantly weaker inter-chain couplings.
• Néel and stripe excitations were identified, with Néel excitations showing sensitivity to Fe impurities.
• Spin excitations in NaFe_{0.53}Cu_{0.47}As exhibit striking similarities to those in quasi-2D FeSe.

Conclusions:

• Magnetic dilution in NaFeAs effectively reduces the dimensionality of its magnetic degrees of freedom.
• The observed quasi-1D spin excitations provide insights into the physics of 1D correlated systems.
• This study presents a viable strategy for discovering and engineering low-dimensional quantum materials through controlled magnetic dilution.