Is the anisotropy of the upper critical field of Sr${}_2$RuO${}_4$ consistent with a helical $p$-wave state?

Abstract

We calculate the angular and temperature $T$ dependencies of the upper critical field $H_{c2}(\theta ,\varphi ,T)$ for the $C_{4v}$ point group helical $p$-wave states, assuming a single uniaxial ellipsoidal Fermi surface, Pauli limiting, and strong spin-orbit coupling that locks the spin-triplet $\vec{\mathbf{d}}$-vectors onto the layers. Good fits to the Sr${}_2$RuO${}_4$ $H_{c2,a}(\theta ,T)$ data of Kittaka {\it et al.} [Phys. Rev. B {\bf 80}, 174514 (2009)] are obtained. Helical states with $\vec{\mathbf{d}}(\vec{\mathbf{k}})=k_x\vec{\mathbf{x}}-k_y\vec{\mathbf{y}}$ and $k_y\vec{\mathbf{x}}+k_x\vec{\mathbf{y}}$ (or $k_x\vec{\mathbf{x}}+k_y\vec{\mathbf{y}}$ and $k_y\vec{\mathbf{x}}-k_x\vec{\mathbf{y}}$) produce $H_{c2}(90^{\circ },\varphi ,T)$ that greatly exceed (or do not exhibit) the four-fold azimuthal anisotropy magnitudes observed in Sr${}_2$RuO${}_4$ by Kittaka {\it et al.} and by Mao {\it et al.} [Phys. Rev. Lett. {\bf 84}, 991 (2000)], respectively.

5+ pages, 4 figures, submitted as a Fast Track Communication to J. Phys. Condens. Matter

References in corpus (6)

• Fulde-Ferrell-Larkin-Ovchinnikov State in Heavy Fermion Superconductors
• Hidden quasi one-dimensional superconductivity in Sr${}_2$RuO${}_4$
• First-Order Superconducting Transition of Sr2RuO4
• Nodeless spin triplet superconducting gap in Sr2RuO4
• Spin Density Wave Fluctuations and p-wave Pairing in Sr2RuO4
• In-plane magnetic field phase diagram of superconducting Sr2RuO4

Cited by in corpus (3)

• Pauli-paramagnetic effects on mixed state properties in a strongly anisotropic superconductor ---Application to Sr_2_RuO_4_---
• Evidence for spin-triplet odd-parity superconductivity close to type-II van Hove singularities
• Inter-orbital p- and d-wave pairings between $d_{xz/yz}$ and $d_{xy}$ orbitals in Sr${}_2$RuO${}_4$