Spin-based information processing is a viable alternative to charge-based approaches, enabling low-power devices. In magnetically ordered systems, spin information can be transported via the quantized excitations of the magnetic lattice, called magnons. In an antiferromagnetic system, we generally find two degenerate magnon modes with opposite Neél precession chirality, i.e., opposite spin. These two modes can couple and give rise to complex dynamics and superposition states. They can be well described via the magnon pseudospin and its dynamics. Electrical pure spin current injection and detection in hematite thin films gives access to the coherent pseudospin dynamics and leads to the manifestation of the magnon Hanle effect. In this project, we investigate the coherent spin dynamics induced by pure spin currents in antiferromagnetic insulators, which open up new avenues for energy-efficient information processing beyond von Neumann architectures.