The direction of the d-vector in a nematic triplet superconductor

Abstract

Abstract We investigate the states of triplet pairing in a candidate nematic superconductor versus typical material parameters, using the mean field theory for two- and three-dimensional tight-binding models with local triplet pairing in the E u representation of the D 3d , the point group of the system. In the two-dimensional model, the system favors the fully gapped chiral state for weaker warping or lower filling level, while a nodal and nematic <?CDATA ${{\rm{\Delta }}}_{4x}$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">Δ</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>4</mml:mn> <mml:mi>x</mml:mi> </mml:mrow> </mml:msub> </mml:math> state is favorable for stronger warping or higher filling, with the d -vector aligned along the principle axis. In the presence of lattice distortion, relative elongation along one of the principle axes, <?CDATA ${\bf{a}}$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi mathvariant="bold">a</mml:mi> </mml:math> , tends to rotate the nematic d -vector orthogonal to <?CDATA ${\bf{a}}$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi mathvariant="bold">a</mml:mi> </mml:math> , resulting in the nematic <?CDATA ${{\rm{\Delta }}}_{4y}$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">Δ</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>4</mml:mn> <mml:mi>y</mml:mi> </mml:mrow> </mml:msub> </mml:math> state at sufficient elongation. Three-dimensionality is seen to suppress the chiral state in favor of the nematic ones. Our results may explain the variety in the probed direction of the d -vector in existing experiments.

Locations

• New Journal of Physics - View - PDF
• arXiv (Cornell University) - View - PDF