Related papers: Possible anisotropic superconducting pairing in cu…
We report Cu nuclear-quadrupole-resonance results under pressure on a homogeneous CeCu2Si2 (Tc = 0.65 K) that revealed critical magnetic fluctuations at the border to an antiferromagnetic phase. This exotic superconducting phase evolves…
Temperature dependencies of excess conductivity, Sigma', have been studied in detail for three FeSe_{0.94} textured polycrystalline samples prepared by partial melting and solid state reaction. It was revealed that both Sigma' and its…
We report the pressure dependences of the superconducting transition temperature (T_c) in several perovskite-type Fe-based superconductors through the resistivity measurements up to ~4 GPa. In Ca_4(Mg,Ti)_3Fe_2As_2O_y with the highest T_c…
The temperature dependence of the in-plane magnetic penetration depth ($\lambda_{ab}$) in an extensively characterized sample of superconducting CaKFe$_4$As$_4$ ($T_{\rm c}\simeq35$ K) was investigated using muon-spin rotation ($\mu$SR). A…
London, $\lambda_L (T)$, and Campbell, $\lambda_{C} (T)$, penetration depths were measured in single crystals of a topological superconductor candidate $\text{AuSn}_4$. At low temperatures, $\lambda_L (T)$ is exponentially attenuated and,…
Paired state of nonstandard quasiparticles is analyzed in detail in two model situations. Namely, we consider the Cooper-pair bound state and the condensed phase of an almost localized Fermi liquid (ALFL) composed of quasiparticles in a…
Satterthwaite and Toepke (1970 Phys. Rev. Lett. 25 741) discovered that Th4H15-Th4D15 superhydrides are superconducting but exhibit no isotope effect. As the isotope effect is a fundamental prediction of electron-phonon mediated…
We study the superconducting density of states and vortex lattice of single crystals of CaKFe$_4$As$_4$ using a scanning tunneling microscope (STM). This material has a critical temperature of $T_c= 35\,$ K, which is one of the highest…
Single crystal of Lu$_2$Fe$_3$Si$_5$ was studied with the tunnel-diode resonator technique in Meissner and mixed states. Temperature dependence of the superfluid density provides strong evidence for the two-gap superconductivity with almost…
UTe2 is a newly discovered unconventional superconductor, where electron Cooper pairs combine into a spin-triplet ground state. Here we report the specific heat C(H,T) of a high-quality single crystal of UTe2 with a single specific heat…
The pressure dependence of the magnetic and superconducting transitions, as well as that of the superconducting upper critical field is reported for CaK(Fe$_{1-x}$Ni$_{x}$)$_4$As$_4$, the first example of an Fe-based superconductor with…
We present measurements of superconducting transition temperature, resistivity, magnetoresistivity and temperature dependence of the upper critical field of Ta$_4$Pd$_3$Te$_{16}$ under pressures up to 16.4 kbar. All measured properties have…
The thermal conductivity of borocarbide superconductor LuNi_2B_2C was measured down to 70 mK (T_c/200) in a magnetic field perpendicular to the heat current from H = 0 to above H_c2 = 7 T. As soon as vortices enter the sample, the…
The superconducting order parameter in the iron-chalcogenide superconductor FeTe$_{0.55}$Se$_{0.45}$ ($T_\textrm{c}$ = 14.2 K) is investigated by point-contact Andreev reflection spectroscopy. The energy gap magnitude (3.8 meV at 1.70 K)…
High critical temperature superconductivity often occurs in systems where an antiferromagnetic order is brought near $T=0K$ by slightly modifying pressure or doping. CaKFe$_4$As$_4$ is a superconducting, stoichiometric iron pnictide…
We have performed transverse-field muon spin relaxation (TF-$\mu$SR) measurements on ambient-pressure-grown polycrystalline $\mathrm{LaO_{0.5}F_{0.5}BiS_{2}}$. From these measurements, no signature of magnetic order is found down to 25 mK.…
We theoretically study superconductivity in UTe$_2$, which is a recently-discovered strong candidate for an odd-parity spin-triplet superconductor. Theoretical studies for this compound faced difficulty because first-principles calculations…
Unconventional superconductivity frequently emerges as the transition temperature of a magnetic phase, typically antiferromagnetic, is suppressed continuously toward zero temperature. Here, we report contrary behavior in pressurized…
75As-zero-field nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements are performed on CaFe2As2 under pressure. At P = 4.7 and 10.8 kbar, the temperature dependences of nuclear-spin-lattice relaxation rate…
We report a systematic study by 75As nuclear-quadrupole resonance in LaFeAsO1-xFx. The antiferromagnetic spin fluctuation (AFSF) found above the magnetic ordering temperature TN = 58 K for x = 0.03 persists in the regime 0.04 < x < 0.08…