Magnetic Structure and Properties of the S = 5/2 Triangular Antiferromagnet $\alpha$-NaFeO$_2$

TL;DR

This study investigates the complex magnetic phases of $ ext{NaFeO}_2$, revealing multiple temperature-dependent magnetic states and highlighting the material's potential for understanding frustrated magnetism.

Contribution

It provides detailed neutron diffraction and magnetization data on $ ext{NaFeO}_2$, showing its rich magnetic phase diagram and emphasizing the need for further theoretical exploration.

Findings

Existence of low-temperature ordered phase with spins along b$_{hex}$ axis

Presence of intermediate incommensurate magnetic phase

Short-range magnetic order persists up to 50 K

Abstract

The magnetic properties of $\alpha$-NaFeO$_2$ are studied by neutron diffraction and magnetization measurements. An ordered phase with spins aligned along the b$_hex$ axis exists at low temperatures (T < 4 K). At intermediate temperatures (4 K < T < 11 K), the system passes through an incommensurate ordered phase before transforming into a short range ordered state at higher temperatures that persists up to at least 50 K. Although the short range ordering does not persist to room temperature according to neutron diffraction, the magnetic susceptibility does not follow Curie-Weiss behavior, even up to 320 K. This rich magnetic behavior can be understood qualitatively as a competition between different magnetic exchange interactions that are similar in magnitude. The delicate balance between these interactions makes $\alpha$-NaFeO$_2$ a candidate for more detailed theoretical work to understand magnetic behavior in frustrated magnetic systems.