Mannig, A., Möller, J. S., Thede, M., Hüvonen, D., Lancaster, T.
, Xiao, F.
, Williams, R.C.
, Guguchia, Z., Khasanov, R., Morenzoni, E. & Zheludev, A. (2016). Effect of disorder on a pressure-induced z = 1 magnetic quantum phase transition. Physical Review B 94
Author(s) from Durham
Pressure-induced ordering close to a z=1 quantum-critical point is studied in the presence of bond disorder in the quantum spin system (C4H12N2)Cu2(Cl1−xBrx)6 (PHCX) by means of muon-spin rotation and relaxation. As for the pure system (C4H12N2)Cu2Cl6, pressure allows PHCX with small levels of disorder (x≤7.5%) to be driven through a quantum-critical point separating a low-pressure quantum paramagnetic phase from magnetic order at high pressures. However, the pressure-induced ordered state is highly inhomogeneous for disorder concentrations x>1%. This behavior might be related to the formation of a quantum Griffiths phase above a critical disorder concentration 7.5%