Quantum phase transition from a spin-liquid state to a spin-glass state in the quasi-one-dimensional spin-1 system Sr_1-xCa_xNi₂V₂O₈

Abstract

We report a quantum phase transition from a spin-liquid state to a spin-glass state in the quasi-one-dimensional (1D) spin-1 system Sr_1-xCa_xNi₂V₂O₈, induced by a small amount of Ca substitution at the Sr site. The ground state of the parent compound (x = 0) is found to be a spin-liquid type with a finite energy gap of 26.6 K between the singlet ground state and the triplet excited state. Both dc-magnetization and ac-susceptibility studies on the highest Ca-substituted compound (x = 0.05) indicate a spin-glass-type magnetic ground state. With increasing Ca concentration, the spin-glass ordering temperature increases from 4.5 K (for the x = 0.015 compound) to 6.25 K (for the x = 0.05 compound). The observed results are discussed in the light of earlier experimental reports and theoretical predictions for a quasi-1D spin-1 system.