Asymmetric Quintuplet Condensation in the Frustrated S = 1 Spin Dimer Compound Ba3Mn2O8

Ba3Mn2O8 is a spin-dimer compound based on pairs of S = 1, 3d(2), Mn5+ ions arranged on a triangular lattice. Antiferromagnetic intradimer exchange leads to a singlet ground state in zero field, with excited triplet and quintuplet states at higher energy. High field thermodynamic measurements are used to establish the phase diagram, revealing a substantial asymmetry of the quintuplet condensate. This striking effect, all but absent for the triplet condensate, is due to a fundamental asymmetry in quantum fluctuations of the paramagnetic phases near the various critical fields.