title: Spin dependent impurity effects on the 2D frustrated magnetism of NiGa2S4.
abstract: Impurity effects on the triangular antiferromagnets Ni1-xMxGa2S4 (M=Mn, Fe, Co and Zn) are studied. The 2D frozen spin-disordered state of NiGa2S4 is stable against the substitution of Zn2+ (S=0) and Heisenberg Fe2+ (S=2) spins, and exhibits a T2-dependent magnetic specific heat, scaled by the Weiss temperature. In contrast, the substitutions with Co2+ (S=3/2) spin with Ising-like anisotropy and Heisenberg Mn2+ (S=5/2) spin induce a conventional spin glass phase below 1 K. From these comparisons, it is suggested that the integer size of the Heisenberg spins is important to stabilize the 2D coherent behavior observed in the frozen spin-disordered state.
authors.affiliation: Department of Physics, Kyoto University, Kyoto 606-8502, Japan and Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Nambu
authors.forename: Satoru
authors.initials: S
authors.lastname: Nakatsuji
authors.forename: Yoshiteru
authors.initials: Y
authors.lastname: Maeno
authors.forename: Edem K
authors.initials: EK
authors.lastname: Okudzeto
authors.forename: Julia Y
authors.initials: JY
authors.lastname: Chan