Reentrant incommensurate order and anomalous magnetic torque in the Kitaev magnet β-Li2Ir O3

We present a theoretical study of the response of β-Li2IrO3 under external magnetic fields in the ab, bc, and ac crystallographic planes. The results are based on the minimal nearest-neighbor J-K-Γ model and reveal a rich intertwining of field-induced phases and magnetic phase transitions with distinctive signatures that can be probed directly via torque magnetometry. Most saliently, we observe (i) an unusual reentrance of the incommensurate counterrotating order for fields in the ab plane and (ii) a set of abrupt torque discontinuities which are particularly large for fields rotating in the bc plane and whose characteristic shape resembles closely the ones observed in the three-dimensional (3D) Kitaev magnet γ-Li2IrO3. An experimental confirmation of these predictions will pave the way for an accurate determination of all relevant microscopic parameters of this 3D Kitaev magnet.