Meta-nematic transitions in a bilayer system: Application to the bilayer ruthenate

TL;DR

This paper explores how bilayer coupling and in-plane magnetic fields influence nematic electronic phases in bilayer systems, explaining experimental anisotropies and revealing new hidden nematic phases.

Contribution

It introduces a bilayer model showing how in-plane magnetic fields affect nematic domain energetics and uncovers a hidden nematic phase preserving Fermi surface symmetry.

Findings

In-plane magnetic field breaks degeneracy of nematic orientations.

Bilayer coupling enables a hidden nematic phase with preserved symmetry.

Pure nematic phase exhibits resistivity anisotropy under in-plane magnetic field.

Abstract

It was suggested that the two consecutive metamagnetic transitions and the large residual resistivity discovered in Sr$_3$Ru$_2$O$_7$ can be understood via the nematic order and its domains in a single layer system. However, a recently reported anisotropy between two longitudinal resistivities induced by tilting the magnetic field away from the c-axis cannot be explained within the single layer nematic picture. To fill the gap in our understanding within the nematic order scenario, we investigate the effects of bilayer coupling and in-plane magnetic field on the electronic nematic phases in a bilayer system. We propose that the in-plane magnetic field in the bilayer system modifies the energetics of the domain formation, since it breaks the degeneracy of two different nematic orientations. Thus the system reveals a pure nematic phase with a resistivity anisotropy in the presence of an in-plane magnetic field. In addition to the nematic phase, the bilayer coupling opens a novel route to a hidden nematic phase that preserves the x-y symmetry of the Fermi surfaces.