Physics and Astronomy, Ames Laboratory
Journal or Book Title
Superconducting gap structure was probed in type-II Dirac semimetal PdTe2 by measuring the London penetration depth using tunnel diode resonator technique. At low temperatures, the data for two samples are well described by weak coupling exponential fit yielding λ(T=0)=230~nm as the only fit parameter at a fixed Δ(0)/Tc≈1.76, and the calculated superfluid density is consistent with a fully gapped superconducting state characterized by a single gap scale. Electrical resistivity measurements for in-plane and inter-plane current directions find very low and nearly temperature-independent normal- state anisotropy. The temperature dependence of resistivity is typical for conventional phonon scattering in metals. We compare these experimental results with expectations from a detailed theoretical symmetry analysis and reduce the number of possible superconducting pairing states in PdTe2 to only three nodeless candidates: a regular, topologically trivial, s-wave pairing, and two distinct odd-parity triplet states that both can be topologically non-trivial depending on the microscopic interactions driving the superconducting instability.
Teknowijoyo, Seram; Jo, Na Hyun; Scheurer, Mathias S.; Tanatar, Makariy A.; Cho, Kyuil; Bud’ko, Sergey L.; Orth, Peter; Canfield, Paul C.; and Prozorov, Ruslan, "Nodeless superconductivity in type-II Dirac semimetal PdTe2: low-temperature London penetration depth and symmetry analysis" (2018). Physics and Astronomy Publications. 484.