Random Spin-orbit Coupling in Spin Triplet Superconductors: Stacking Faults in Sr_2RuO_4 and CePt_3Si

Abstract

The random spin-orbit coupling in multicomponent superconductors is investigated focusing on the non-centrosymmetric superconductor CePt_3Si and the spin triplet superconductor Sr_2RuO_4. We find novel manifestations of the random spin-orbit coupling in the multicomponent superconductors with directional disorders, such as stacking faults. The presence of stacking faults is indicated for the disordered phase of CePt_3Si and Sr_2RuO_4. It is shown that the d-vector of spin triplet superconductivity is locked to be d = k_y x - k_x y with the anisotropy ΔT_c/T_c0 \sim \barα^2/T_c0 W_z, where \barα, T_c0, and W_z are the mean square root of random spin-orbit coupling, the transition temperature in the clean limit, and the kinetic energy along the c-axis, respectively. This anisotropy is much larger (smaller) than that in the clean bulk Sr_2RuO_4 (CePt_3Si). These results indicate that the helical pairing state d = k_y x - k_x y in the eutectic crystal Sr_2RuO_4-Sr_3Ru_2O_7 is stabilized in contrast to the chiral state d = (k_x \pm i k_y) z in the bulk Sr_2RuO_4. The unusual variation of T_c in CePt_3Si is resolved by taking into account the weak pair-breaking effect arising from the uniform and random spin-orbit couplings. These superconductors provide a basis for discussing recent topics on Majorana fermions and non-Abelian statistics.

J. Phys. Soc. Jpn. 79 (2010) 084701

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• Complex-Stripe Phases Induced by Staggered Rashba Spin-Orbit Coupling
• Parity-Mixed Superconductivity in Locally Non-centrosymmetric System
• Spin-sensitive Long-ranged Proximity Effect for Triplet Superconductors
• Spin-orbit Coupling and Multiple Phases in Spin-triplet Superconductor Sr${}_2$RuO${}_4$
• Magnetic parity violation and parity-time-reversal-symmetric magnets
• Spin-Orbit Coupling in Multilayer Superconductors with Charge Imbalance
• Field-induced superconductivity mediated by odd-parity multipole fluctuation
• Doping Dependence of Spin-Momentum Locking in Bismuth-Based High-Temperature Cuprate Superconductors
• Momentum space imaging of locally noncentrosymmetric superconductors
• Spin and charge order in doped spin-orbit coupled Mott insulators