Magnetism and superconductivity inMcTa2S2C(

Abstract

Magnetic properties of McTa2S2C (M = Fe, Co, Ni, Cu) have been studied using SQUID DC and AC magnetic susceptibility. In these systems magnetic M 2+ ions are intercalated into van der Waals gaps between adjacent S layers of host superconductor Ta2S2C. Fe0.33Ta2S2C is a quasi 2D XY -like antiferromagnet on the triangular lattice. It undergoes an antiferromagnetic phase transition at TN (= 117 K). The irreversible effect of magnetization occurs below TN , reflecting the frustrated nature of the system. The AF phase coexists with two superconducting phases with the transition temperatures Tcu = 8.8 K and T cl = 4.6 K. Co0.33Ta2S2C is a quasi 2D Isinglike antiferromagnet on the triangular lattice. The antiferromagnetic phase below TN = 18.6 K coexists with a superconducting phase below Tcu = 9.1 K. Both Ni0.25Ta2S2C and Cu0.60Ta2S2C are superconductors with Tcu (= 8.7 K for Ni and 6.4 K for Cu) and T cl (= 4.6 K common to McTa2S2C). Very small effective magnetic moments suggest that Ni 2+ and Cu 2+ spins are partially delocalized.

Aging dynamics in a reentrant ferromagnet:Cu0.2Co0.8Cl2−FeCl3Suzuki1, Suzuki2 2005Phys. Rev. BSelf Cite3240View full textAdd to dashboardCite

“…The static and dynamic behavior of the RSG phase is characterized by that of the normal SG phase: a critical exponent β = 0.57 ± 0.10 for the SG parameter and a dynamic critical exponent x = 8.5±1.8 for the characteristic relaxation time. 11 The aging phenomena are clearly seen in the RSG phase, although no appreciable nonlinear magnetic susceptibility is observed. The exponent n for the stretched exponential relaxation exhibits a local minimum just below T RSG , and increases when T approaches T RSG from the low-T side.…”

“…11 The detail of the sample characterization and synthesis were presented in the references of the previous paper. 11 The DC magnetization and AC susceptibility of Cu 0.2 Co 0.8 Cl 2 -FeCl 3 GBIC were measured using a SQUID magnetometer (Quantum Design, MPMS XL-5) with an ultra low field capability option. The remnant magnetic field was reduced to zero field (exactly less than 3 mOe) at 298 K for both DC magnetization and AC susceptibility measurements.…”

“…The exponent λ q at T SG is described by λ q (T SG ) = β/x, where x is the dynamic critical exponent and β is the exponent of the SG order parameter. In the previous paper 11 we have reported the values of β and x as β = 0.57 and x = 8.5, leading to λ q = 0.067. The agreement between the theory and experiment is very good.…”

“…In previous paper 11 we have reported the f dependence of the equilibrium absorption χ ′′ (ω, T ) at various T in the vicinity of T RSG , respectively. The absorption χ ′′ (ω, T ) curves exhibit different characteristics depending on T .…”

“…The static and dynamic magnetic properties have been reported in a previous paper. 11 This compound undergoes successive transitions at the transition temperatures T c (= 9.7 K) and T RSG (= 3.5 K). A prominent nonlinear susceptibility is observed between T RSG and T c , suggesting a chaotic nature of the FM phase.…”