科研之友
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摘要
We present data for the temperature dependence of the magnetic penetration depth lambda(T), heat capacity C(T), resistivity rho(T), and magnetic torque tau for highly homogeneous single-crystal samples of Fe1.0Se0.44(4)Te0.56(4). lambda(T) was measured down to 200 mK in zero field. We find lambda(T) follows a power law Delta lambda similar to T-n with n = 2.2 +/- 0.1. This is similar to some 122 iron arsenides and likely results from a sign-changing pairing state combined with strong scattering. Magnetic fields of up to B=55 or 14 T were used for the tau(B) and C(T)/rho(T) measurements, respectively. The specific heat, resistivity, and torque measurements were used to map out the (H,T) phase diagram in this material. All three measurements were conducted on exactly the same single-crystal sample so that the different information revealed by these probes is clearly distinguished. Heat-capacity data strongly resemble those found for the high-T-c cuprates, where strong fluctuation effects wipe out the phase transition at H-c2. Unusually, here we find the fluctuation effects appear to be strongly anisotropic.
- 出版日期2010-9-20
