Field-orientation dependence of quantum phase transitions in the S=1/2 triangular-lattice antiferromagnet Ba3CoSb2O9

Ba3CoSb2O9 approximates the two-dimensional spin-1/2 triangular-lattice Heisenberg antiferromagnet. This compound displays magnetic-field-induced quantum phase transitions, including the 1/3-magnetization plateau, but its magnetization processes for the magnetic field H parallel and perpendicular to the c axis are different due to the weak easy-plane anisotropy and the weak interlayer antiferromagnetic exchange interaction. To elucidate how the quantum phase transitions change between these two field directions, we measured the field-angle dependence of the magnetization process in Ba3CoSb2O9 using pulsed high-magnetic fields. We compared obtained magnetic-field-field-angle phase diagram with those obtained by the large-size cluster mean-field method combined with a scaling scheme and the semiclassical theory. We also found a narrow 1/3-magnetization plateau and a high-field transition with a small magnetization jump for H parallel to c, not observed in the previous studies.

Automated summary

This study investigates the field-angle dependence of the magnetization process in Ba3CoSb2O9 and compares the results with other methods. The research reveals different magnetization behaviors in Ba3CoSb2O9 under different field directions, including a narrow 1/3-magnetization plateau and a high-field transition with a small magnetization jump.