Z₂Vortex-Induced Broadening of the EPR Linewidth in the Two-Dimensional Triangular Lattice Antiferromagnets, HCrO₂and LiCrO₂

Li7NMR studies on the triangular lattice systemLiCrO2<

“…This is corroborated by the temperature dependence of the 7 Li nuclear spin-lattice relaxation rate 1 / T 1 ͑T͒ above T N which was modeled to arise from free moving vortices in the LiCrO 2 lattice. Our value of T KTB = 54 K is similar to that estimated by Ajiro et al 26 of 60 K. Heat capacity data at low temperatures ͑T Ͻ ϽT N ͒ exhibited a T 3 dependence and yielded the ratio of interlayer and intralayer coupling constants in LiCrO 2 , J Ќ / J to be around 10 −3 . Lithium depletion does not have a significant effect on the magnetic properties of LiCrO 2 in contrast to Na depletion in isostructural NaCoO 2 .…”

“…25͒, and four free parameters ␣, ␤, b, and T KTB . The corresponding T KTB for LiCrO 2 was found to be 54 K which is close to the value obtained by Ajiro et al 26 of 60 K and might explain the temperature dependence of the spinlattice relaxation rate above T N . A smaller prefactor ␣ = 0.14Ͻ 1 than expected ͑␣ =1͒ might arise due to a wavevector q ជ dependence of the hyperfine coupling.…”

Design of Spin-Frustrated Monomer-Type C60•− Mott Insulator

“…Numerous inorganic compounds have been examined based on this idea. A few examples are VX2 (X = Cl, Br) [15], ABO2 [16][17][18][19][20][21] (A = monocation, B = trivalent transition metal ions: CuFeO2 [16][17][18], LiNiO2 [19], NaTiO2, [19], LiCrO2 [20][21][22]), ABX3 [23,24] (X = halogenide ions: CsCoCl3 [23], CsMnBr3 [24]), and large clusters (Mo72Fe30, Mo72V20) [25] for the triangular lattice, and KFe3(SO4)2(OH)6 [26][27][28] and Rb2SnCu3F12 [29] for the kagome lattice. Some typical magnetically frustrated inorganic systems of transition metal oxides studied prior 2000 have been summarized by Ramirez [13] and Greedan [4].…”

7Li NMR Studies of LiCrO2

“…The Weiss temperature Θ is estimated to be -700 K from the Curie-Weiss susceptibility fit above about 450 K [1]. The spin frustration effects on the paramagnetic state and the magnetic ordered state have been explored by using ESR [2], neutron diffraction [3], NMR and thermodynamic properties [4] and muon spin rotation (µSR) [5]. The temperature dependences of the ESR line width [2] and 7 Li NMR spin-echo relaxation rate [4] were associated with an exponential increase of thermally excited Z 2 vortices (topological defects) [6].…”

“…The spin frustration effects on the paramagnetic state and the magnetic ordered state have been explored by using ESR [2], neutron diffraction [3], NMR and thermodynamic properties [4] and muon spin rotation (µSR) [5]. The temperature dependences of the ESR line width [2] and 7 Li NMR spin-echo relaxation rate [4] were associated with an exponential increase of thermally excited Z 2 vortices (topological defects) [6]. However, three dimensional magnetic structure with double-Q 120 • ordering vectors has been observed in the neutron diffraction [3] and µSR [5].…”