Weak ferromagnetism at 48.5 K in rubidium-intercalated biphenyl

Aromatic hydrocarbon molecules with it-conjugated structure have great potential for the search of exotic states such as high temperature superconductivity and novel quantum magnetism. In this work, we found that high temperature weak ferromagnetism can be achieved by intercalating rubidium into the shortest poly(para-phe-nylene) molecule-biphenyl. Both dc and ac magnetic susceptibility measurements showed that the synthesized material exhibits a typical antiferromagnetic transition at 48.5 K, accompanying a ferromagnetic character in the magnetically ordered region. Combining theoretical calculations and Raman spectroscopic studies, it was found that the mole ratio between rubidium and biphenyl is 1:1, and the molecular magnetic moments are formed by transferring the Rb-5s electrons to the C-2p orbitals. The weak ferromagnetism is produced by intralayer spin -canted antiferromagnetic and interlayer ferromagnetic spin couplings. Our finding enriches the physicochem-ical functionality of biphenyl and opens a window for the search of it-electron organic magnets in poly(para- phenylene) molecules.

Automated summary

In this study, high temperature weak ferromagnetism was achieved by intercalating rubidium into the shortest poly(para-phenylene) molecule-biphenyl. The synthesized material exhibited a typical antiferromagnetic transition at 48.5 K, accompanied by a ferromagnetic character in the magnetically ordered region. The weak ferromagnetism was produced by intralayer spin-canted antiferromagnetic and interlayer ferromagnetic spin couplings. This finding enriches the physicochemical functionality of biphenyl and provides a new avenue for the search of it-electron organic magnets in poly(para-phenylene) molecules.