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Spin-orbit coupling enhanced superconductivity in Bi-rich compounds ABi₃ (A = Sr and Ba).

Shao DF, Luo X, Lu WJ, Hu L, Zhu XD, Song WH, Zhu XB, Sun YP - Sci Rep (2016)

Bottom Line: Without SOC, strong Fermi surface nesting leads to phonon instabilities in ABi3.SOC suppresses the nesting and stabilizes the structure.ABi3 can be potential platforms to construct heterostructure of superconductor/topological insulator to realize topological superconductivity.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China.

ABSTRACT
Recently, Bi-based compounds have attracted attentions because of the strong spin-orbit coupling (SOC). In this work, we figured out the role of SOC in ABi3 (A = Sr and Ba) by theoretical investigation of the band structures, phonon properties, and electron-phonon coupling. Without SOC, strong Fermi surface nesting leads to phonon instabilities in ABi3. SOC suppresses the nesting and stabilizes the structure. Moreover, without SOC the calculation largely underestimates the superconducting transition temperatures (Tc), while with SOC the calculated Tc are very close to those determined by measurements on single crystal samples. The SOC enhanced superconductivity in ABi3 is due to not only the SOC induced phonon softening, but also the SOC related increase of electron-phonon coupling matrix elements. ABi3 can be potential platforms to construct heterostructure of superconductor/topological insulator to realize topological superconductivity.

No MeSH data available.


Related in: MedlinePlus

Band structures and Fermi surface of BaBi3.(a) The band dispersion of BaBi3 with (the red lines) and without (grey lines) SOC. (b–e) are the Fermi surface of BaBi3 with SOC, while (f–i) are those without SOC. The blue arrows in (i) denotes the nesting vectors M and R.
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f6: Band structures and Fermi surface of BaBi3.(a) The band dispersion of BaBi3 with (the red lines) and without (grey lines) SOC. (b–e) are the Fermi surface of BaBi3 with SOC, while (f–i) are those without SOC. The blue arrows in (i) denotes the nesting vectors M and R.

Mentions: We also calculated the properties of BaBi3. The substitution of Sr by Ba changes the crystal from cubic to tetragonal structure. However, the lattice parameters of a (5.188 Å) and that of c (5.136 Å) are very close to each other. Therefore, the resulted band structure and Fermi surface of BaBi3 (Fig. 6) are very similar to those of SrBi3. Our calculation is in good agreement with previous report18. SOC remarkably lifts the band degeneracy near Fermi energy (EF) in all the symmetry directions of BaBi3 as well (Fig. 6(a)). Four bands cross EF, formatting three hole pockets around the body center of the Brillouin Zone (Γ), two hole pockets around the corner of the Brillouin Zone (A), and two electron pockets locating at the face centers (X and Z) and edge centers (M and R), respectively (Fig. 6(b–i)).


Spin-orbit coupling enhanced superconductivity in Bi-rich compounds ABi₃ (A = Sr and Ba).

Shao DF, Luo X, Lu WJ, Hu L, Zhu XD, Song WH, Zhu XB, Sun YP - Sci Rep (2016)

Band structures and Fermi surface of BaBi3.(a) The band dispersion of BaBi3 with (the red lines) and without (grey lines) SOC. (b–e) are the Fermi surface of BaBi3 with SOC, while (f–i) are those without SOC. The blue arrows in (i) denotes the nesting vectors M and R.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4759591&req=5

f6: Band structures and Fermi surface of BaBi3.(a) The band dispersion of BaBi3 with (the red lines) and without (grey lines) SOC. (b–e) are the Fermi surface of BaBi3 with SOC, while (f–i) are those without SOC. The blue arrows in (i) denotes the nesting vectors M and R.
Mentions: We also calculated the properties of BaBi3. The substitution of Sr by Ba changes the crystal from cubic to tetragonal structure. However, the lattice parameters of a (5.188 Å) and that of c (5.136 Å) are very close to each other. Therefore, the resulted band structure and Fermi surface of BaBi3 (Fig. 6) are very similar to those of SrBi3. Our calculation is in good agreement with previous report18. SOC remarkably lifts the band degeneracy near Fermi energy (EF) in all the symmetry directions of BaBi3 as well (Fig. 6(a)). Four bands cross EF, formatting three hole pockets around the body center of the Brillouin Zone (Γ), two hole pockets around the corner of the Brillouin Zone (A), and two electron pockets locating at the face centers (X and Z) and edge centers (M and R), respectively (Fig. 6(b–i)).

Bottom Line: Without SOC, strong Fermi surface nesting leads to phonon instabilities in ABi3.SOC suppresses the nesting and stabilizes the structure.ABi3 can be potential platforms to construct heterostructure of superconductor/topological insulator to realize topological superconductivity.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China.

ABSTRACT
Recently, Bi-based compounds have attracted attentions because of the strong spin-orbit coupling (SOC). In this work, we figured out the role of SOC in ABi3 (A = Sr and Ba) by theoretical investigation of the band structures, phonon properties, and electron-phonon coupling. Without SOC, strong Fermi surface nesting leads to phonon instabilities in ABi3. SOC suppresses the nesting and stabilizes the structure. Moreover, without SOC the calculation largely underestimates the superconducting transition temperatures (Tc), while with SOC the calculated Tc are very close to those determined by measurements on single crystal samples. The SOC enhanced superconductivity in ABi3 is due to not only the SOC induced phonon softening, but also the SOC related increase of electron-phonon coupling matrix elements. ABi3 can be potential platforms to construct heterostructure of superconductor/topological insulator to realize topological superconductivity.

No MeSH data available.


Related in: MedlinePlus