Highly entangled magnetodielectric coupling, magnetostriction, and spin-phonon coupling phenomena in Ni 2 ScSbO 6

Magnetic compounds with noncentrosymmetric chiral crystal structures and spin-frustrated lattices often exhibit complex magnetic ordering and coupled responses. In this report, we present a comprehensive study of the chiral and triangular lattice magnetic system Ni2ScSbO6, which exhibits an incommensurate noncollinear helical antiferromagnetic long-range ordering at a temperature of TN = 62 K, as revealed by bulk magnetization, specific heat, and neutron diffraction studies. The onset of this magnetic ordering is closely linked to a series of strongly coupled phenomena occurring at TN. A clear dielectric anomaly in the form of a sharp λ-like peak is observed at TN, triggered by an isostructural distortion, which is mediated by the magnetostriction effect in this system, as evidenced by our synchrotron x-ray diffraction studies. Moreover, a clear anomalous phonon softening for various Raman modes is observed at TN, which can be attributed to substantial spin-phonon coupling combined with the influence of magnetostriction effects. All these strongly correlated phenomena, occurring concurrently with the emergence of the helical antiferromagnetic order, demonstrate an entangled behavior of various microscopic degrees of freedom in this system, thus highlighting Ni2ScSbO6 as a unique material.