One-dimensional quantum antiferromagnetism in the $p-$orbital CsO${}_2$ compound revealed by electron paramagnetic resonance

Abstract

Recently it was proposed that the orbital ordering of ${\pi }_{x,y}^{\ast }$ molecular orbitals in the superoxide CsO${}_2$ compound leads to the formation of spin-1/2 chains below the structural phase transition occuring at $T_{s1}=61$~K on cooling. Here we report a detailed X-band electron paramagnetic resonance (EPR) study of this phase in CsO${}_2$ powder. The EPR signal appears as a broad line below $T_{s1}$, which is replaced by the antiferromagnetic resonance below the Néel temperature $T_{\mathrm{N}}=8.3$~K. The temperature dependence of the EPR linewidth between $T_{s1}$ and $T_{\mathrm{N}}$ agrees with the predictions for the one-dimensional Heisenberg antiferromagnetic chain of $S=1/2$ spins in the presence of symmetric anisotropic exchange interaction. Complementary analysis of the EPR lineshape, linewidth and the signal intensity within the Tomonaga-Luttinger liquid (TLL) framework allows for a determination of the TLL exponent $K=0.48$. Present EPR data thus fully comply with the quantum antiferromagnetic state of spin-1/2 chains in the orbitally ordered phase of CsO${}_2$, which is, therefore, a unique $p-$orbital system where such a state could be studied.

6 pages, 3 figures

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Cited by in corpus (9)

• Phonon-modulated magnetic interactions and spin Tomonaga-Luttinger liquid in the p-orbital antiferromagnet CsO2
• Control of the third dimension in copper-based square-lattice antiferromagnets
• Superconductivity in the regime of attractive interactions in the Tomonaga-Luttinger liquid
• Spin-dimer ground state driven by consecutive charge and orbital ordering transitions in the anionic mixed-valence compound Rb${}_4$O${}_6$
• Magnetism and high-magnetic field magnetization in alkali superoxide CsO2
• Spin-gap formation due to spin-Peierls instability in $\pi$-orbital-ordered NaO${}_2$
• Correlation-driven metal-insulator transition in unconventional magnetic metal superoxides
• The crystal and magnetic structure of cesium superoxide
• Spin-Orbital Ordering in Alkali Superoxides