1205.6164 (Jing Wang et al.)

Competition between superconductivity and nematic order in high-$T_c$
superconductor    [PDF]

Jing Wang, Guo-Zhu Liu

We investigate the competition between superconductivity and nematic order in d-wave high-$T_c$ superconductor. Apart from the competitive interaction with superconducting order, the nematic order also couples strongly to gapless nodal quasiparticles. The interplay of these two interactions is analyzed by means of renormalization group method. An interesting consequence of ordering competition is the appearance of runaway behavior for some specific parameters, which implies an instability of first order transition. We show that the ratio between gap velocity and Fermi velocity, $\kappa = v_\Delta/v_F$, of nodal quasiparticles plays a crucial role in determining the fixed point of the system. As $\kappa$ decreases, the possibility of first order transition is enhanced. At the nematic critical point where $\kappa \rightarrow 0$ driven by the critical nematic fluctuation, no stable fixed point exists and first order transition becomes inevitable. Our results indicate that gapless fermionic degrees of freedom should be taken into account in the theoretical description of competing orders.

View original: http://arxiv.org/abs/1205.6164