Vortex states of the E_{u} model for Sr_{2}RuO_{4}

TL;DR

This paper investigates vortex states in Sr_{2}RuO_{4} using the E_{u} Ginzburg-Landau model, predicting multiple phase transitions and vortex lattice deformations that can help validate the model.

Contribution

It provides detailed theoretical predictions of vortex phase transitions and lattice structures in Sr_{2}RuO_{4} based on the E_{u} symmetry model.

Findings

Presence of a second superconducting transition regardless of field direction.

Development of a double-peak structure in magnetic-field distribution.

Deformation of vortex lattice from square to rectangular as field decreases.

Abstract

Based on the Ginzburg-Landau functional of E_{u} symmetry presented by Agterberg, vortex states of Sr_{2}RuO_{4} are studied in detail over $H_{c1}\lesssim H \leq H_{c2}$ by using the Landau-level expansion method. For the field in the basal plane, it is found that (i) the second superconducting transition should be present irrespective of the field direction; (ii) below this transition, a characteristic double-peak structure may develop in the magnetic-field distribution; (iii) a third transition may occur between two different vortex states. It is also found that, when the field is along the c axis, the square vortex lattice may deform through a second-order transition into a rectangular one as the field is lowered from H_{c2}. These predictions will be helpful in establishing the E_{u} model for Sr_{2}RuO_{4}.