Study of Integer Spin = 1 in the Polar Magnet β-Ni(IO).

Polar magnetic materials exhibiting appreciable asymmetric exchange interactions can potentially host new topological states of matter such as vortex-like spin textures; however, realizations have been mostly limited to half-integer spins due to rare numbers of integer spin systems with broken spatial inversion lattice symmetries. Here, we studied the structure and magnetic properties of the = 1 integer spin polar magnet β-Ni(IO) (Ni, d, F). We synthesized single crystals and bulk polycrystalline samples of β-Ni(IO) by combining low-temperature chemistry techniques and thermal analysis and characterized its crystal structure and physical properties. Single crystal X-ray and powder X-ray diffraction measurements demonstrated that β-Ni(IO) crystallizes in the noncentrosymmetric polar monoclinic structure with space group 2. The combination of the macroscopic electric polarization driven by the coalignment of the (IO) trigonal pyramids along the axis and the = 1 state of the Ni cation was chosen to investigate integer spin and lattice dynamics in magnetism. The effective magnetic moment of Ni was extracted from magnetization measurements to be 3.2(1) µ, confirming the = 1 integer spin state of Ni with some orbital contribution. β-Ni(IO) undergoes a magnetic ordering at = 3 K at a low magnetic field, = 0.1 T; the phase transition, nevertheless, is suppressed at a higher field, = 3 T. An anomaly resembling a phase transition is observed at ≈ 2.7 K in the C/ vs. plot, which is the approximate temperature of the magnetic phase transition of the material, indicating that the transition is magnetically driven. This work offers a useful route for exploring integer spin noncentrosymmetric materials, broadening the phase space of polar magnet candidates, which can harbor new topological spin physics.