title: Crystal growth and ambient and high pressure study of the re-entrant superconductor Tm(2)Fe(3)Si(5).
abstract: Tm(2)Fe(3)Si(5) is known to undergo a transition to the superconducting state (at ambient or applied pressure depending on the sample) at a temperature T(c1)(∼1.8 K), and at a lower temperature T(N)(≈1 K) it undergoes a transition into a long range antiferromagnetically ordered state. Superconductivity is simultaneously destroyed and the sample re-enters the normal state at T(c2) = T(N). The conditions reported in the literature for the observation of superconductivity in Tm(2)Fe(3)Si(5) are sample dependent, but it is now accepted that stoichiometric Tm(2)Fe(3)Si(5) superconducts only under pressure. Here we report single-crystal growth of stoichiometric Tm(2)Fe(3)Si(5) which does not superconduct at ambient pressure down to 100 mK. Measurements of the anisotropic static magnetic susceptibility χ(T) and isothermal magnetization M(H), ac susceptibility χ(ac)(T), electrical resistivity ρ(T) and heat capacity C(T) at ambient pressure and χ(ac)(T) at high pressure are reported. The magnetic susceptibility along the c axis, χ(c)(T), shows a curvature over the whole temperature range and does not follow the Curie-Weiss behavior, while the magnetic susceptibility along the a axis, χ(a)(T), follows a Curie-Weiss behavior between 130 and 300 K with a Weiss temperature θ and an effective magnetic moment μ(eff) which depend on the temperature range of the fit. The easy axis of magnetization is perpendicular to the c axis and χ(a)/χ(c) = 3.2 at 1.8 K. The ambient pressure χ(ac)(T) and C(T) measurements confirm bulk antiferromagnetic ordering at T(N) = 1.1 K. The sharp drop in χ(ac)(T) below the antiferromagnetic transition is suggestive of the existence of a spin gap. We observe superconductivity only under applied pressures P≥2 kbar. The temperature-pressure phase diagram showing the non-monotonic dependence of the superconducting transition temperature T(c) on pressure P is presented.
authors.forename: Yogesh
authors.initials: Y
authors.lastname: Singh
authors.forename: S
authors.initials: S
authors.lastname: Ramakrishnan