New Realisations of Frustrated Quantum Spin Systems from Vanadium Based Oxyfluorides

We recently presented the first example of a material containing a kagome network of antiferromagnetically interacting V$^{4+}$ $S={\frac{1}{2}}$ cations, DQVOF (Diammonium Quinuclidinium Vanadium OxyFluoride). The $S={\frac{1}{2}}$ kagome layers within DQVOF are separated by V$^{3+}$ $S=1$ cations. Our low temperature magnetic study of DQVOF suggested that the kagome layers remain decoupled from these inter-layer spins and that the system adopts a gapless QSL ground state [1]. Here, we will discuss how variations in the chemical methods used to prepare DQVOF can be employed to extend this family of frustrated V$^{4+}$ based oxyfluorides. In particular, we will focus on a new phase ImVOF (Imidazolium Vanadium OxyFluoride), which consists of V$^{4+}$ $S={\frac{1}{2}}$ kagome layers like DQVOF, but the connectivity between the kagome layers is remarkably different. Single crystal X-ray diffraction reveals that the inter-layer vanadium species in ImVOF also sit on a kagome network. Magnetic susceptibility data of ImVOF reveal an absence of long range magnetic magnetic order down to $2$ K despite significant antiferromagnetic exchange exchange (${\theta}{\sim} -50$ K), which suggests that interesting physics is at play.\\[4pt] [1] L. Clark et al., Phys. Rev. Lett. 110, 207208 ($2013$)