Properties of an organic model S=1 Haldane chain system

doi:10.1103/PhysRevB.111.064407

Properties of an organic model S=1 Haldane chain system

2025-02-03

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DOI：10.1103/PhysRevB.111.064407

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We present the properties of an organic S = 1 antiferromagnetic chain system m-NO2PhBNO (abbreviated BoNO). In this biradical system, two unpaired electrons from aminoxyl groups are strongly ferromagnetically coupled (|JFM|/kB >= 500 K), which leads to the formation of an effective S = 1 state for each molecule. The chains of BoNO biradicals propagate along the crystallographic a axis. Temperature dependencies 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 a Haldane system with an almost isotropic g factor (2.0023 +/- 2 parts per thousand). The magnetization measurements in magnetic fields up to 40 T and low-field susceptibility, together with 1H nuclear magnetic resonance (NMR) spectra, reveal a dominant intrachain antiferromagnetic exchange coupling of J1D/kB = (11.3 +/- 0.1) K, and attainable critical magnetic fields of mu 0Hc1 2 T and mu 0Hc2 33 T. These measurements therefore suggest that BoNO is a rare example of a Haldane system with extremely small magnetic anisotropy. The present results are crucial for a future in-depth NMR study of the low-temperature Tomonaga-Luttinger liquid and magnetic field-induced phases, which can be performed in the entire phase space.

Keywords:

MAGNETIC-PROPERTIES

EPR FREQUENCIES

GROUND-STATE

EXCHANGE

NITROXIDE)

CRYSTAL

Properties of an organic model S=1 Haldane chain system

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