Commensurate Itinerant Antiferromagnetism in BaFe2As2: 75As-NMR Studies on a Self-Flux Grown Single Crystal

TL;DR

This study uses 75As-NMR to investigate the magnetic and structural transitions in BaFe2As2, revealing a first-order antiferromagnetic transition with stripe spin structure and anisotropic spin fluctuations.

Contribution

It provides detailed NMR evidence for the stripe antiferromagnetic order and structural transition in BaFe2As2, highlighting the development of anisotropic spin fluctuations.

Findings

First-order AF transition near 135 K detected by NMR line splitting.

Simultaneous structural transition evidenced by electric field gradient change.

Development of anisotropic stripe-type spin fluctuations in the paramagnetic phase.

Abstract

We report results of 75As nuclear magnetic resonance (NMR) experiments on a self-flux grown single crystal of BaFe2As2. A first-order antiferromagnetic (AF) transition near 135 K was detected by the splitting of NMR lines, which is accompanied by simultaneous structural transition as evidenced by a sudden large change of the electric field gradient tensor at the As site. The NMR results lead almost uniquely to the stripe spin structure in the AF phase. The data of spin-lattice relaxation rate indicate development of anisotropic spin fluctuations of the stripe-type with decreasing temperature in the paramagnetic phase.