Commensurate and incommensurate magnetic order in spin-1 chains stacked on the triangular lattice inLi2NiW2O8

Abstract

We report thermodynamic properties, magnetic ground state, and microscopic magnetic model of the spin-1 frustrated antiferromaget Li2NiW2O8 showing successive transitions at TN1 18 K and TN2 12.5 K in zero field. Nuclear magnetic resonance and neutron diffraction reveal collinear and commensurate magnetic order with the propagation vector k = ( 1 2 , 0, 1 2 ) below TN2. The ordered moment of 1.8 µB at 1.5 K is directed along [0.89(9), −0.10(5), −0.49 (6)] and matches the magnetic easy axis of spin-1 Ni 2+ ions, which is determined by the scissor-like distortion of the NiO6 octahedra. Incommensurate magnetic order, presumably of spin-density-wave type, is observed in the region between TN2 and TN1. Density-functional band-structure calculations put forward a three-dimensional spin lattice with spin-1 chains running along the [011] direction and stacked on a spatially anisotropic triangular lattice in the ab plane. We show that the collinear magnetic order in Li2NiW2O8 is incompatible with the triangular lattice geometry and thus driven by a pronounced easy-axis single-ion anisotropy of Ni 2+ . a O3 O2 O1 O2 ' c b J 011 J 100 x z J 010 J 110

Unraveling the complex magnetic structure of multiferroic pyroxene NaFeGe2O6 : A combined experimental and theoretical study

“…The frustration itself, the competition between J 2 and J 3 , does not split the transition into two, and the presence of weak single-ion anisotropy seems to be crucial here. Similar combinations of the cycloid and SDW phases were observed in systems like Ca 3 Co 2 O 6 [42,43] and Li 2 NiW 2 O 8 [44], where magnetic ions bear strong single-ion anisotropy. Although Fe 3+ with its half-filled d-shell is by far less anisotropic than Ni 2+ or Co 3+ , the anisotropy energy of less than 1 K (and less than 1% of the leading exchange coupling J 1 ) is already sufficient for driving similar physics.…”

Frustration of square cupola in Sr(TiO) Cu4(PO4)4

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Frustrated three-dimensional antiferromagnetLi2CuW2O8:Li7Ranjith1, Majumder2, Baenitz3 et al. 2015Phys. Rev. BSelf Cite19691View full textAdd to dashboardCite

“…14, 15 Many of the triangular-lattice compounds exhibit two phase transitions at low temperatures too. 16 The presence of only one magnetic transition and the robust collinear order in Li 2 CuW 2 O 8 are clearly unusual and require detailed investigation.…”