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arXiv · 0902.1336

Microscopic theory of the nematic phase in Sr$_3$Ru$_2$O$_7$

S. Raghu·A. Paramekanti·E. -A. Kim·R. A. Borzi·S. Grigera·A. P. Mackenzie·S. A. Kivelson
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Abstract

In an externally applied magnetic field, ultra-pure crystals of the bilayer compound Sr$_3$Ru$_2$O$_7$ undergo a metamagnetic transition below a critical temperature, $T^*$, which varies as a function of the angle between the magnetic field $H$ and the Ru-O planes. Moreover, $T^*$ approaches zero when $H$ is perpendicular to the planes. This putative "metamagnetic quantum critical point", however, is preempted by a nematic fluid phase with order one resistive anisotropy in the {\it ab} plane. In a "realistic" bilayer model with moderate strength local Coulomb interactions, the existence of a sharp divergence of the electronic density of states near a van Hove singularity of the quasi-one-dimensional bands, and the spin-orbit couplings permitted by the presence of multiple orbitals result in a mean-field phase diagram which accounts for many of these experimentally observed phenomena. Although the spin-orbit coupling is not overly strong, it destroys the otherwise near perfect Fermi surface nesting and hence suppresses spin-density-wave (SDW) ordering.

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S. Raghu, A. Paramekanti, E. -A. Kim, R. A. Borzi, S. Grigera, A. P. Mackenzie, S. A. Kivelson. 2009-06-01. Microscopic theory of the nematic phase in Sr$_3$Ru$_2$O$_7$. https://doi.org/10.1103/physrevb.79.214402

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