Pristine quantum criticality in a Kondo semimetal.

The observation of quantum criticality in diverse classes of strongly correlated electron systems has been instrumental in establishing ordering principles, discovering new phases, and identifying the relevant degrees of freedom and interactions. At focus so far have been insulators and metals. Semimetals, which are of great current interest as candidate phases with nontrivial topology, are much less explored in experiments.

Anomalous normal fluid response in a chiral superconductor UTe.

Chiral superconductors have been proposed as one pathway to realize Majorana normal fluid at its boundary. However, the long-sought 2D and 3D chiral superconductors with edge and surface Majorana normal fluid are yet to be conclusively found. Here, we report evidence for a chiral spin-triplet pairing state of UTe with surface normal fluid response.

Low-temperature crystal structure of the unconventional spin-triplet superconductor UTe from single-crystal neutron diffraction.

The crystal structure of a new superconductor UTe has been investigated using single-crystal neutron diffraction for the first time at the low temperature (LT) of 2.7 K, just above the superconducting transition temperature of ∼1.6 K, in order to clarify whether the orthorhombic structure of type Immm (No.

Point-node gap structure of the spin-triplet superconductor UTe.

Low-temperature electrical and thermal transport, magnetic penetration depth, and heat capacity measurements were performed on single crystals of the actinide superconductor UTe to determine the structure of the superconducting energy gap. Heat transport measurements performed with currents directed along both crystallographic and axes reveal a vanishingly small residual fermionic component of the thermal conductivity. The magnetic field dependence of the residual term follows a rapid, quasilinear increase consistent with the presence of nodal quasiparticles, rising toward the -axis upper critical field where the Wiedemann-Franz law is recovered.

Extreme magnetic field-boosted superconductivity.

Applied magnetic fields underlie exotic quantum states, such as the fractional quantum Hall effect and Bose-Einstein condensation of spin excitations. Superconductivity, however, is inherently antagonistic towards magnetic fields. Only in rare cases can these effects be mitigated over limited fields, leading to re-entrant superconductivity.