Magnetism and superconductivity in $M_{c}$Ta$_{2}$S$_{2}$C (M = Fe, Co, Ni, and Cu)

Masatsugu Suzuki; Itsuko S. Suzuki; Jürgen Walter

doi:10.1103/PhysRevB.71.224407

paper

Magnetism and superconductivity in $M_{c}$ Ta $_{2}$ S $_{2}$ C (M = Fe, Co, Ni, and Cu)

arXiv:cond-mat/0402501 · doi:10.1103/PhysRevB.71.224407

Abstract

Magnetic properties of $M_{c}$ Ta $_{2}$ S $_{2}$ C ( $M$ = 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 Ta $_{2}$ S $_{2}$ C. Fe $_{0.33}$ Ta $_{2}$ S $_{2}$ C is a quasi 2D $X Y$ -like antiferromagnet on the triangular lattice. It undergoes an antiferromagnetic phase transition at $T_{N}$ (= 117 K). The irreversible effect of magnetization occurs below $T_{N}$ , reflecting the frustrated nature of the system. The AF phase coexists with two superconducting phases with the transition temperatures $T_{c u} = 8.8$ K and $T_{c l} = 4.6$ K. Co $_{0.33}$ Ta $_{2}$ S $_{2}$ C is a quasi 2D Ising-like antiferromagnet on the triangular lattice. The antiferromagnetic phase below $T_{N} = 18.6$ K coexists with a superconducting phase below $T_{c u} = 9.1$ K. Both Ni $_{0.25}$ Ta $_{2}$ S $_{2}$ C and Cu $_{0.60}$ Ta $_{2}$ S $_{2}$ C are superconductors with $T_{c u}$ ( $= 8.7$ K for Ni and 6.4 K for Cu) and $T_{c l}$ (= 4.6 K common to $M_{c}$ Ta $_{2}$ S $_{2}$ C). Very small effective magnetic moments suggest that Ni $^{2 +}$ and Cu $^{2 +}$ spins are partially delocalized.

15 pages, 17 figures, and 3 tables

Magnetism and superconductivity in Mc​Ta2​S2​C (M = Fe, Co, Ni, and Cu)

Abstract

Magnetism and superconductivity in $M_{c}$ Ta $_{2}$ S $_{2}$ C (M = Fe, Co, Ni, and Cu)