Properties of an organic model \(S=1\) Haldane chain system

We present the properties of a new organic \(S=1\) chain system \(m\)-NO\(_2\)PhBNO (abbreviated BoNO). In this biradical system two unpaired electrons from aminoxyl groups are strongly ferromagnetically coupled (\(|J_\text{FM}| \gtrsim 500\) K) which leads to the formation of an effective \(S=1\) s...

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Bibliographic Details
Published in:arXiv.org 2024-10
Main Authors: Jakovac, Ivan, Cvitanić, Tonči, Arčon, Denis, Herak, Mirta, Cinčić, Dominik, Nea Baus Topić, Hosokoshi, Yuko, Ono, Toshio, Iwashita, Ken, Hayashi, Nobuyuki, Amaya, Naoki, Matsuo, Akira, Kindo, Koichi, Lončarić, Ivor, Horvatić, Mladen, Takigawa, Masashi, Grbić, Mihael S
Format: Article
Language:English
Subjects:
Antiferromagnetism
Crystallography
Electron paramagnetic resonance
Electrons
Extreme values
Ferromagnetism
Low temperature
Magnetic anisotropy
Magnetic fields
NMR
Nuclear magnetic resonance
Temperature dependence
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Summary:We present the properties of a new organic \(S=1\) chain system \(m\)-NO\(_2\)PhBNO (abbreviated BoNO). In this biradical system two unpaired electrons from aminoxyl groups are strongly ferromagnetically coupled (\(|J_\text{FM}| \gtrsim 500\) K) which leads to the formation of an effective \(S=1\) state for each molecule. The chains of BoNO diradicals propagate along the crystallographic \(a\) axis. Temperature dependence of the \(g\) factor and electron paramagnetic resonance (EPR) linewidth are consistent with a low-dimensional system with antiferromagnetic interactions. The EPR data further suggest that BoNO is the first known Haldane system with an almost isotropic \(g\) factor (\(2.0023 \pm 2 \unicode{x2030}\)). The magnetization measurements in magnetic fields up to \(40\) T and low-field susceptibility, together with \(^1\)H nuclear magnetic resonance (NMR) spectra, reveal a dominant intrachain antiferromagnetic exchange coupling of \(J_\text{1D} = (11.3\pm0.1)\) K, and attainable critical magnetic fields of \(\mu_0 H_\text{c1} \approx 2\) T and \(\mu_0 H_\text{c2} \approx 33\) T. These measurements therefore suggest that BoNO is a unique Haldane system with extremely small magnetic anisotropy. Present results are crucial for a future in-depth NMR study of the low-temperature Tomonaga-Luttinger liquid (TLL) and magnetic field-induced phases, which can be performed in the entire phase space.
ISSN:2331-8422