Quantum criticality in the kagome staircase system Co$_3$V$_2$O$_8$ in transverse magnetic field

Co$_3$V$_2$O$_8$ (CVO) belongs to the kagome staircase family of orthorhombic materials in which Ising-like Co$^{2+}$, S=3/2 magnetic moments decorate a stacked and buckled version of the two-dimensional kagome lattice. In zero applied magnetic field, this material displays a complex series of five different magnetically ordered phases below $\sim$11 K which culminate in a simple ferromagnetic state below Tc$\sim$6 K. Previous inelastic neutron scattering work[1] on this quasi-two-dimensional system showed that the exchange interactions within the kagome planes are rather weak (J$\sim$1.25 meV), making this system an ideal candidate for the study of transverse field-induced quantum critical phenomena as have been observed in LiHoF$_4$ or recently in CoNb$_2$O$_6$. We have investigated the phase diagram of CVO with the transverse field applied along the stacking direction using magnetization as well as single crystal neutron scattering techniques. We will discuss how the ground state magnetic structure and spin dynamics of CVO evolve upon tuning the transverse magnetic field through the quantum critical point near Hc$\sim$6 T. [1] M. Ramazanoglu et al., PRB 79, 024417 (2009).