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Here we present a comprehensive study of the effect of hydrostatic pressure on the magnetic structure and spin dynamics in a spin-1/2 coupled ladder antiferromagnet C₉H₁₈N₂CuBr₄ (DLCB for short). In DLCB, the inter-ladder coupling is sufficiently strong to drive the system to the long-range antiferromagnetic ordering phase below T_N=2.0 K [1]. Analysis of the spin Hamiltionian suggests that DLCB is close to the quantum critical point in two dimensions at ambient pressure and zero field [2]. The single-crystal heat capacity and neutron diffraction measurements suggets that the magnetic order breaks down above a critical pressure P_c~1.0 GPa. By contrasting with quantum Monte Carlo calculations of the dynamic structure factor, the follow-up inelastic neutron scattering above P_c reveals evidence of a Z₂ spin-liquid phase in terms of characteristic fully gapped vison-like and fractionalized excitations in the distinct scattering channels.

References:
[1] Hong et al., Phys. Rev. B 89, 174432 (2014).
[2] Hong et al., Nat. Phys. 13, 638 (2017).