Pressure- and field-induced magnetic quantum phase transitions in TlCuCl₃

TlCuCl₃ is a quantum spin liquid of S = 1/2 Cu²⁺ diraers. Interdimer superexchange interactions give a three-dimensional rnagnon dispersion and a spin gap significantly smaller than the dimer coupling, which is closed by an applied hydrostatic pressure of approximately 2.5 kbar or by a magnetic field of 5.6 T, offering a unique opportunity to explore both the pressure- and field-induced quantum phase transitions and their associated critical phenomena.