Abstract
Strong spin orbital interaction (SOI) can induce unique quantum phenomena such as topological insulators, the Rashba effect, or p-wave superconductivity. Combining these three quantum phenomena into a single compound has important scientific implications. Here we report experimental observations of consecutive quantum phase transitions from a Rashba type topological trivial phase to topological insulator state then further proceeding to superconductivity in a SOI compound BiTeI tuned via pressures. The electrical resistivity measurement with V shape change signals the transition from a Rashba type topological trivial to a topological insulator phase at 2 GPa, which is caused by an energy gap close then reopen with band inverse. Superconducting transition appears at 8 GPa with a critical temperature TC of 5.3 K. Structure refinements indicate that the consecutive phase transitions are correlated to the changes in the Bi–Te bond and bond angle as function of pressures. The Hall Effect measurements reveal an intimate relationship between superconductivity and the unusual change in carrier density that points to possible unconventional superconductivity.
Highlights
Studies on the systems of strong spin orbital interactions (SOI), which play important roles in forming novel quantum states, intensively grown[1,2,3,4,5,6,7,8]
This paper reports on the discovery of superconductivity in BiTeI induced by pressure that borders the transition from a Rashba type topological trivial state to a topological insulator state
The low resistance of the BiTeI crystal is generally caused by additional conductivity by certain defects mentioned in ref
Summary
Rashba Type Topological Transition received: 24 October 2016 accepted: 24 November 2016. Strong spin orbital interaction (SOI) can induce unique quantum phenomena such as topological insulators, the Rashba effect, or p-wave superconductivity. Combining these three quantum phenomena into a single compound has important scientific implications. We report experimental observations of consecutive quantum phase transitions from a Rashba type topological trivial phase to topological insulator state further proceeding to superconductivity in a SOI compound BiTeI tuned via pressures. Similar to TIs, topological superconductors are expected to have gapless edge (or surface) states that can host long sought elusive Majorana fermions Such unconventional superconductors are potentially important for new quantum computers[7,8]. Structure evolutions, including local structure distortion at high pressures, are investigated by Raman spectroscopy in conjunction with high pressure synchrotron X-ray diffraction
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