Emergence of intrinsic superconductivity below 1.178 K in the topologically non-trivial semimetal state of CaSn₃

Abstract

Topological materials which are also superconducting are of great current interest, since they may exhibit a non-trivial topologically-mediated superconducting phase. Although there have been many reports of pressure-tuned or chemical-doping-induced superconductivity in a variety of topological materials, there have been few examples of intrinsic, ambient pressure superconductivity in a topological system having a stoichiometric composition. Here, we report that the pure intermetallic CaSn3 not only exhibits topological fermion properties, but also has a superconducting phase at ~1.178 K under ambient pressure. The topological fermion properties, including the nearly zero quasi-particle mass and the non-trivial Berry phase accumulated in cyclotron motions, were revealed from the de Haas-van Alphen (dHvA) quantum oscillation studies of this material. Although CaSn3 was previously reported to be superconducting with Tc =

Fermi surfaces of the topological semimetal CaSn$_{3}$ probed through de Haas van Alphen oscillations

“…2b and c, nodes in the beating patterns produce π phase shifts in the oscillations. While the frequencies of F α , F β , and F γ are in good agreement with those previously reported [10], F δ that is prominent above 30 T (or 1/B < 0.033 T −1 ) is newly identified by the present work.…”

“…The observed frequencies F are associated with ex- lar to the previous report [10]. The dHvA frequencies extracted from the FFT analysis exhibit nearly isotropic angular dependence for the α, β, γ, and δ orbits, as shown in fig.…”

“…We confirmed the cubic AuCu 3 -type structure with space group P m 3m with the lattice constant of a = 4.7331(5) Å via powder x-ray diffraction. No Sn impurities were observed unlike the previous reports [9,10]. Torque magnetometry was performed using a capacitive cantilever in a 35 T resistive magnet at the National High Magnetic Field Laboratory (NHMFL), Tallahassee, FL.…”

de Haas-van Alphen Quantum Oscillations in BaSn3 Superconductor with Multiple Dirac Fermions*

“…Up to now, the physical properties of ASn 3 have been less studied as compared with LnM 3 . The recent studies on CaSn 3 have revealed it as a weakly coupled type-II superconductor hosting eight pairs of WPs in the BZ with closed loops of surface Fermi arcs [47][48][49]. In light of the intriguing properties of CaSn 3 , investigation on the analogue BaSn 3 in terms of the electronic structure to examine possible nontrivial topological states is very valuable.…”

Photoemission Spectroscopic Evidence of Multiple Dirac Cones in Superconducting BaSn3

“…Recently, superconducting compounds ASn 3 (A=Ca or Ba) were predicted to host topological semimetal states [58][59][60][61][62] . Studies on the topology in the weak coupling superconductor CaSn 3 propose that it hosts topological nodal-line semimetal states in the absent of spin-orbital coupling (SOC) and would evolve to Weyl nodes with SOC [58][59][60] . While, its relatively complicated band structure impedes the direct investigation of the nontrivial band topology therein.…”