Magnetic structure and properties of the honeycomb antiferromagnet [Na(OH${}_2$)${}_3$]Mn(NCS)${}_3$

Abstract

We report the magnetic structure and properties of a thiocyanate-based honeycomb magnet [Na(OH${}_2$)${}_3$]Mn(NCS)${}_3$ which crystallises in the unusual low-symmetry trigonal space group $P\overline{3}$. Magnetic measurements on powder samples show this material is an antiferromagnet (ordering temperature ($T_{\mathrm{N},\mathrm{mag}}=18.1(6)$)K) and can be described by nearest neighbour antiferromagnetic interactions $J=-11.07(4)$K. A method for growing neutron-diffraction sized single crystals (\textgreater10 mm${}^3$) is demonstrated. Low temperature neutron single crystal diffraction shows that the compound adopts the collinear antiferromagnetic structure with $T_{\mathrm{N},\mathrm{neut}}=18.94(7)$K, magnetic space group $P{\bar{3}}^{\prime }$. Low temperature second-harmonic generation (SHG) measurements provide no evidence of breaking of the centre of symmetry.

4 pages +references, 3 figures