Towards Equilateral Triangular Lattice Frustrated Quantum Magnets through Molecular-brick Chemical Strategy

Equilateral triangular lattices (TLs) with antiferromagnetic interactions are ideal templates for inducing magnetic frustration, offering a platform to explore exotic quantum spin states, which are crucial for advancing quantum science and technology. However, few examples meet these structural criteria, and even fewer realize these fascinating physical properties. Here, we report four novel equilateral TL magnets by deliberately choosing the structural template and building blocks, namely, the molecular-brick chemical strategy. Magnetic ions are fixed on an equilateral TL via a three-fold rotation symmetry in the a-b plane and are eclipsed stacked along the c-axis. Magnetic susceptibility and specific heat measurements reveal a long-range magnetic ordering in BaCoBe2(BO3)2F2 around 180 mK, while BaNiBe2(BO3)2F2 remains disordered at 140 mK. Furthermore, crystal orbital Hamilton population analysis shows that different molecular bricks exhibit distinct bonding characteristics, resulting in diverse magnetic properties. Our results demonstrate that the molecular-brick chemical strategy offers valuable insights for investigating geometrically frustrated magnets.