Stripe order and magnetic anisotropy in the S=1 antiferromagnet BaMoP2 O8

Abstract

Magnetic behavior of yavapaiite-type BaMoP2O8 with the spatially anisotropic triangular arrangement of the S=1Mo4+ ions is explored using thermodynamic measurements, neutron diffraction, and density-functional band-structure calculations. A broad maximum in the magnetic susceptibility around 46 K is followed by the stripe antiferromagnetic order with the propagation vector k=(12,12,12) formed below TN≃21 K. This stripe phase is triggered by a pronounced one-dimensionality of the spin lattice, where one of the in-plane couplings, J2≃4.6 meV, is much stronger than its J1≃0.4 meV counterpart, and stabilized by the weak easy-axis anisotropy. The ordered moment of 1.42(9)μB at 1.5 K is significantly lower than the spin-only moment of 2μB due to a combined effect of quantum fluctuations and spin-orbit coupling. © 2018 American Physical Society.