Transport evidence for three dimensional topological superconductivity in doped $\beta$-PdBi${}_2$

Abstract

Interest in topological states of matter exploded over a decade ago with the theoretical prediction and experimental detection of three-dimensional topological insulators, especially in bulk materials that can be tuned out of it by doping. However, their superconducting counterpart, the time-reversal invariant three-dimensional topological superconductor, has evaded discovery thus far. In this work, we provide transport evidence that K-doped $\beta$-PdBi${}_2$ is a 3D time-reversal-invariant topological superconductor. In particular, we find signatures of Majorana surface states protected by time-reversal symmetry--the hallmark of this phase--in soft point-contact spectroscopy, while the bulk system shows signatures of odd-parity pairing via upper-critical field and magnetization measurements. Odd-parity pairing can be argued, using existing knowledge of the band structure of $\beta$-PdBi${}_2$, to result in 3D topological superconductivity. Moreover, we find that the undoped system is a trivial superconductor. Thus, we discover $\beta$-PdBi${}_2$ as a unique material that, on doping, can potentially undergo an unprecedented topological quantum phase transition in the superconducting state.

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Cited by in corpus (9)

• A comprehensive review on topological superconducting materials and interfaces
• Power-law Temperature Dependence of the Penetration Depth in a Topological Superconductor due to Surface States
• Massive suppression of proximity pairing in topological (Bi${}_{1-x}$Sb${}_x{)}_2$Te${}_3$ films on niobium
• Large spin to charge conversion in topological superconductor \b{eta}-PdBi2 at room temperature
• Unconventional pressure dependence of the superfluid density in the nodeless topological superconductor $\alpha$-PdBi${}_2$
• Topological nodal $i$-wave superconductivity in PtBi${}_2$
• Low-temperature thermal expansion of the topological material candidates $\beta$-PtBi${}_2$ and $\beta$-Bi${}_2$Pd
• How spectrum-wide quantum criticality protects surface states of topological superconductors from Anderson localization: Quantum Hall plateau transitions (almost) all the way down
• Sn2Pd: a possible superconducting material with topological surface states