Realization of insulating state and superconductivity in the Rashba semiconductor BiTeCl

Abstract

Layered non-centrosymmetric bismuth tellurohalides are being examined as candidates for topological insulators. Pressure is believed to be essential for inducing and tuning topological order in these systems. Through electrical transport and Raman scattering measurements, we find superconductivity in two high-pressure phases of BiTeCl with the different normal state features, carrier characteristics, and upper critical field behaviors. Superconductivity emerges when the resistivity maximum or charge density wave is suppressed by the applied pressure and then persists till the highest pressure of 51 GPa measured. The huge enhancement of the resistivity with three magnitude of orders indicates the possible achievement of the topological order in the dense insulating phase. These findings not only enrich the superconducting family from topological insulators but also pave the road on the search of topological superconductivity in bismuth tellurohalides.PACS numbers: 74.62. Fj, 74.25.Dw, Topological insulators represent the newly discovered phase of matter with insulating bulk state but topologically protected metallic surface state due to the timereversal symmetry and strong spin-orbital interaction [1,2]. Searching for topological superconductivity is one of the hottest topics due to the exploration of fundamental physics and the potential applications in topological quantum computation [3,4] [15]. However, the identification of their topological superconductivity is still a hard task and under debate [7,9]. In most cases, pressure is needed to drive topological insulators to superconductors. Superconductivity is usually accompanied by the electronic topological transition and/or structural transition [6,11]. It remains unclear whether such a transition is essential for inducing superconductivity in topological insulators.The class of non-centrosymmetric bismuth tellurohalides (BiTeX with X=Cl, Br, I) exhibit large Rashbatype splittings in the bulk bands [16][17][18][19][20], and they are potential candidates for building the spintronic devices. Pressure-induced topological quantum phase transition was predicted for Rashba semiconductor BiTeI [21]. However, controversial conclusions were drawn from the following experiments on this material [22,23]. Recently, BiTeCl was discovered to be the first example of inversion asymmetric topological insulator (IATI) from angleresolved photoemission spectroscopy (ARPES) experiment [24]. This was soon supported by the transport measurement [25]. Unlike the previously discovered three dimensional topological insulators with inversion symmetry, the inversion symmetry is naturally broken by the crystal structure in IATI. It is highly possible to realize the topological magneto-electric effects and the topological superconductivity [24,26,27]. However, quantum oscillation measurements excluded the existence of Dirac surface state in BiTeCl single crystals [28,29]. Such contradiction may come from the strong surface polarity which would generate large effective pressure along the ...

Pressure-driven superconductivity in the transition-metal pentatellurideHfTe5

“…Considering the close similarities in ambient-pressure properties and the pressure-driven behavior of both pentatellurides, it might be supposed that the SC-II phase in ZrTe2 is rather a metastable state characteristic only for this compound. The negligible variation of Tc over a very large range of pressure observed for both pentatellurides is highly unusual, however a similar effect was observed for the pressure-induced superconductivity in some topologically nontrivial systems such as Bi2Se3 29 and BiTeCl 30 .…”

Structural, vibrational, and electrical study of compressed BiTeBr

“…* Corresponding author: juasant2@upvnet.upv.es Furthermore, several pressure-induced phase transitions have been discovered in BiTeI, the properties of which have not been studied in detail [14][15][16]18]. Additionally, BiTeCl has been recently found to become superconducting at high pressures [19], but whether it is the first topological superconductor ever observed is still under discussion. These examples just show that high-pressure studies are important to understand the exotic properties of bismuth tellurohalides.…”

Pressure-Induced Large Volume Collapse, Plane-to-Chain, Insulator to Metal Transition in CaMn2Bi2

“…[51][52][53] This tool has long been used, for example, to tune semiconductors, superconductors, and other solid-state materials to better understand their band structures and probe the electronic levels that arise from defects or impurities. [54][55][56][57][58][59][60][61][62][63][64][65][66][67] Pressure is particularly useful because the effects it induces are typically not associated with large changes in entropy, and therefore it frequently does not obscure subtle phase transitions. As a consequence, atomic and magnetic interaction parameters such as orbital energy and orbital overlap can be tuned and detected under pressure, and in the quantum material CaMn2Bi2 may potentially enhance the interplay between SOC and magnetism.…”