Triangular Magnet Emergent from Noncentrosymmetric Sr_0.94Mn_0.86Te_1.14O₆ Single Crystals

Abstract

We report the successful growth of high-quality single crystals of Sr 0.94 Mn 0.86 Te 1.14 O 6 (SMTO) using a self-flux method. The structural, electronic, and magnetic properties of SMTO are investigated by neutron powder diffraction (NPD), single-crystal X-ray diffraction (SCXRD), thermodynamic, and nuclear magnetic resonance techniques in conjunction with density functional theory calculations. NPD unambiguously determined octahedral (trigonal antiprismatic) coordination for all cations with the chiral space group P312 (no. 149), which is further confirmed by SCXRD data. The Mn and Te elements occupy distinct Wyckoff sites, and minor anti-site defects were observed in both sites. X-ray photoelectron spectroscopy reveals the existence of mixed valence states of Mn in SMTO. The magnetic susceptibility and specific heat data evidence a weak antiferromagnetic order at T N = 6.6 K. The estimated Curie−Weiss temperature θ CW = −21 K indicates antiferromagnetic interaction between Mn ions. Furthermore, both the magnetic entropy and the 125 Te nuclear spin−lattice relaxation rate showcase that short-range spin correlations persist well above the Neél temperature. Our work demonstrates that Sr 0.94(2) Mn 0.86(3) Te 1.14(3) O 6 single crystals realize a noncentrosymmetric triangular antiferromagnet.

Successive short- and long-range magnetic ordering in rosiaite-type CoGeTeO6 prepared by ion-exchange reaction

“…Similar structures were also formed with heterovalent combinations of (M′ 4+ , Te 6+ ) (M′ = Mn, Ge, Sn) in place of two Sb 5+ ions, i.e. , PbMnTeO 6 , 11,12 “SrMnTeO 6 ” (actually nonstoichiometric), 13 MGeTeO 6 (M = Mn, Cd, Pb), 14 and MnSnTeO 6 . 15 One more type of rosiaite-related phase has the formula R 3+ M 3+ TeO 6 , where R = rare earth or Bi, and M = Cr, Mn or Fe.…”

“…1a). Replacing two Sb atoms with two different elements within the honeycomb layers eliminates the mirror plane and inversion symmetries, leading to chiral structures as found for MGeTeO 6 (M = Mn, Cd, Pb), 14 PbMnTeO 6 , 12 “SrMnTeO 6 ”, 13 and BiMTeO 6 (M = Al, Ga), 22 which have a single-layered structure (Fig. 1b) with the space group P 312 and no superlattice reflection.…”