Magnetic phase diagrams of the Kagomé staircase compound Co₃ V₂ O₈

At zero magnetic field, a series of five phase transitions occur in Co₃ V₂ O₈. The Néel temperature, T_N = 11.4 K, is followed by four additional phase changes at T₁ = 8.9 K, T₂ = 7.0 K, T₃ = 6.9 K, and T₄ = 6.2 K. The different phases are distinguished by the commensurability of the b-component of its spin density wave vector. We investigate the stability of these various phases under magnetic fields through dielectric constant and magnetic susceptibility anomalies. The field-temperature phase diagram of Co₃ V₂ O₈ is completely resolved. The complexity of the phase diagram results from the competition of different magnetic states with almost equal ground state energies due to competing exchange interactions and frustration.