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Vestigial nematic order and superconductivity in the doped topological insulator CuₓBi₂Se₃

Hecker, Matthias; Schmalian, Jörg

If the topological insulator Bi2Se3 is doped with electrons, superconductivity with Tc = 3–4 K emerges for a low density of carriers (n = 1020 cm−3) and with a small ratio of the superconducting coherence length and Fermi wave length: ξ/λ F  = 2…4. These values make fluctuations of the superconducting order parameter increasingly important, to the extend that the Tc-value is surprisingly large. Strong spin–orbit interaction led to the proposal of an odd-parity pairing state. This begs the question of the nature of the transition in an unconventional superconductor with strong pairing fluctuations. We show that for a multi-component order parameter, these fluctuations give rise to a nematic phase at Tnem > Tc. Below Tc several experiments demonstrated a rotational symmetry breaking where the Cooper pair wave function is locked to the lattice. Our theory shows that this rotational symmetry breaking, as vestige of the superconducting state, already occurs above Tc. The nematic phase is characterized by vanishing off-diagonal long range order, yet with anisotropic superconducting fluctuations. It can be identified through direction-dependent para-conductivity, lattice softening, and an enhanced Raman response in the Eg symmetry channel. ... mehr

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Verlagsausgabe §
DOI: 10.5445/IR/1000083166
Veröffentlicht am 04.06.2018
DOI: 10.1038/s41535-018-0098-z
Zitationen: 9
Web of Science
Zitationen: 10
Zugehörige Institution(en) am KIT Institut für Theorie der Kondensierten Materie (TKM)
Institut für Festkörperphysik (IFP)
Publikationstyp Zeitschriftenaufsatz
Jahr 2018
Sprache Englisch
Identifikator ISSN: 2397-4648
KITopen-ID: 1000083166
HGF-Programm 43.21.01 (POF III, LK 01)
Erschienen in npj quantum materials
Band 3
Heft 1
Seiten Article: 26
Bemerkung zur Veröffentlichung Gefördert durch den KIT-Publikationsfonds
Vorab online veröffentlicht am 16.05.2018
Schlagworte Phase transitions and critical phenomena; Superconducting properties and materials
Nachgewiesen in Web of Science
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