Time-reversal symmetry breaking and spontaneous Hall effect without magnetic dipole order

Chiral spin liquids are a hypothetical class of spin liquids in which time-reversal symmetry is macroscopically broken even in the absence of an applied magnetic field or any magnetic dipole long-range order. Although such spin-liquid states were proposed more than two decades ago, they remain elusive. Here, evidence is presented that the time-reversal symmetry can be broken spontaneously on a macroscopic scale in the absence of magnetic dipole long-range order, suggesting the emergence of a chiral spin liquid.