Niu Q, Knebel G, Braithwaite D, Aoki D, Lapertot G, Seyfarth G, Brison J-P, Flouquet J, Pourret A
Université Grenoble Alpes, CEA, IRIG, PHELIQS, F-38000 Grenoble, France.
Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313, Japan.
Phys Rev Lett. 2020 Feb 28;124(8):086601. doi: 10.1103/PhysRevLett.124.086601.
Transport measurements are presented up to fields of 29 T in the recently discovered heavy-fermion superconductor UTe_{2} with magnetic field H applied along the easy magnetization a axis of the body-centered orthorhombic structure. The thermoelectric power varies linearly with temperature above the superconducting transition, T_{SC}=1.5 K, indicating that superconductivity develops in a Fermi liquid regime. As a function of field the thermoelectric power shows successive anomalies which appear at critical values of the magnetic polarization. Remarkably, the lowest magnetic field instability for H∥a occurs for the same critical value of the magnetization (0.4 μ_{B}) than the first order metamagnetic transition at 35 T for field applied along the b axis. It can be clearly identified as a Lifshitz transition. The estimated number of charge carriers at low temperature reveals a metallic ground state distinct from LDA calculations indicating that strong electronic correlations are a major issue.
在最近发现的重费米子超导体UTe₂中，沿体心正交结构的易磁化a轴施加磁场H，给出了高达29 T磁场下的输运测量结果。在超导转变温度Tₛₑ = 1.5 K以上，热电功率随温度线性变化，这表明超导性是在费米液体状态下发展起来的。作为磁场的函数，热电功率显示出连续的异常现象，这些异常出现在磁极化的临界值处。值得注意的是，对于H∥a，最低磁场不稳定性出现时的磁化临界值（0.4 μ₈）与沿b轴施加35 T磁场时的一级变磁转变相同。它可以被明确识别为里夫希茨转变。低温下估计的载流子数量揭示了一个与局域密度近似计算不同的金属基态，这表明强电子关联是一个主要问题。
