Antiferromagnetic structure of alkali metal superoxide CsO${}_2$

Abstract

We have performed a powder neutron diffraction study on CsO${}_2$, where the unpaired electron with $s=1/2$ in the ${\pi }^{\ast }$ orbital of the O${}_2^{-}$ ion is responsible for the magnetism. The magnetic reflections 0 $\frac{1}{2}$ 0 and 0 $\frac{1}{2}$ 1 were observed below the Néel temperature of about 10 K. An antiferromagnetic structure with a propagation vector of (0 ,$\frac{1}{2}$, 0) and magnetic moments parallel to the $a$-axis is the most plausible. The magnitude of the ordered moment is about 0.2 ${\mu }_B$, which is considered to be strongly suppressed due to the one-dimensionality of the system. We propose a possible ${\pi }^{\ast }$ orbital order that can explain the obtained magnetic structure, and discuss its relation to the one-dimensionality.

References in corpus (2)

• Antiferromagnetic order driven by the molecular orbital order of C${}_{60}$ in ${\alpha }^{\prime }$--tetra--$kis$--(dimethylamino)--ethylene--C${}_{60}$
• Spin-gap formation due to spin-Peierls instability in $\pi$-orbital-ordered NaO${}_2$

Cited by in corpus (2)

• Spin-Orbital Ordering in Alkali Superoxides
• The crystal and magnetic structure of cesium superoxide