Crystal growth and ambient and high pressure study of the re-entrant superconductor Tm2Fe3Si5

Tm2Fe3Si5 is known to undergo a transition to the superconducting state (at ambient or applied pressure depending on the sample) at a temperature T-c1 (similar to 1.8 K), and at a lower temperature T-N (approximate to 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 Tm2Fe3Si5 are sample dependent, but it is now accepted that stoichiometric Tm2Fe3Si5 superconducts only under pressure. Here we report single-crystal growth of stoichiometric Tm2Fe3Si5 which does not superconduct at ambient pressure down to 100 mK. Measurements of the anisotropic static magnetic susceptibility chi(T) and isothermal magnetization M(H), ac susceptibility chi(ac)(T), electrical resistivity rho(T) and heat capacity C(T) at ambient pressure and chi(ac)(T) at high pressure are reported. The magnetic susceptibility along the c axis, chi(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, chi(a)(T), follows a Curie-Weiss behavior between 130 and 300 K with a Weiss temperature theta and an effective magnetic moment mu(eff) which depend on the temperature range of the fit. The easy axis of magnetization is perpendicular to the c axis and chi(a)/chi(c) = 3.2 at 1.8 K. The ambient pressure chi(ac)(T) and C(T) measurements confirm bulk antiferromagnetic ordering at T-N = 1.1 K. The sharp drop in chi(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.