Anomalous Temperature Dependence of Lower Critical Field in Ultraclean URu${}_2$Si${}_2$

Abstract

To investigate a mysterious superconducting state of URu_2Si_2 embedded in the so-called hidden order state, the lower critical field H_{c1} is precisely determined down to 55 mK for H || a and H || c. For this purpose, the positional dependence of the local magnetic induction is measured on ultraclean single crystals (T_c = 1.4 K) with residual resistivity ratio exceeding 700. We find that the temperature dependence of H_{c1} significantly differs from that of any other superconductors. The whole H_{c1}(T) for H || a are well explained by the two superconducting gap structures with line and point nodes, which have been suggested by the recent thermal conductivity and specific heat measurements. On the other hand, for H || c, a change of slope with a distinct kink in H_{c1}(T), which cannot be accounted for by two gaps, is observed. This behavior for H || c sharply contrasts with the cusp behavior of H_{c1}(T) associated with a transition into another superconducting phase found in UPt_3 and U_{1-x}Th_xBe_{13}. The observed anomalous low-field diamagnetic response is possibly related to a peculiar vortex dynamics associated with chiral domains due to the multicomponent superconducting order parameter with broken time reversal symmetry.

7 pages, 4 figures; accepted in J. Phys. Soc. Jpn

References in corpus (10)

• Superconducting phases of f-electron compounds
• High Resolution Polar Kerr Effect Measurements of Sr2RuO4: Evidence for Broken Time Reversal Symmetry in the Superconducting State
• Magnetic Penetration Depth in Unconventional Superconductors
• Exotic Superconducting Properties in the Electron-Hole Compensated Heavy Fermion `Semimetal' URu2Si2
• Why the hidden order in URu2Si2 is still hidden - one simple answer
• Lower Critical Fields of Superconducting PrFeAsO${}_{1-y}$ Single Crystals
• Possible Phase Transition Deep Inside the Hidden Order Phase of Ultraclean URu2Si2
• Flux Line Lattice Melting and the Formation of a Coherent Quasiparticle Bloch State in the Ultraclean URu${}_2$Si${}_2$ Superconductor
• Vortex Redistribution below the First-Order Transition Temperature in the β-Pyrochlore Superconductor KOs_2O_6
• Anomalous Thermal Conductivity of Semi-Metallic Superconductors with Electron-Hole Compensation

Cited by in corpus (10)

• Rotational Symmetry Breaking in the Hidden-Order Phase of URu2Si2
• A review of two-band superconductivity: materials and effects on the thermodynamic and reversible mixed-state properties
• Colossal thermomagnetic response in the exotic superconductor URu2Si2
• Superfluid density and carrier concentration across a superconducting dome: the case of SrTi${}_{1-x}$Nb${}_x$O${}_3$
• Broken symmetries in URu2Si2
• Anisotropic Enhancement of Lower Critical Field in Ultraclean Crystals of Spin-Triplet Superconductor UTe2
• Thermodynamic evidence for broken fourfold rotational symmetry in the hidden-order phase of URu2Si2
• Hidden order symmetry and superconductivity in URu2Si2 investigated by quasiparticle interference
• Chiral superconductivity in nematic states
• Lower Critical Field Hc1(T) and Pairing Symmetry Based on Eilenberger Theory