Stability of Highly Entangled Metallic States

We study the stability of a class of highly entangled metallic states, such as orthogonal metals

under thermal and quantum fluctuations. First, it is explicitly shown that the highly entangled

states in layered states are stable, while they become unstable in strict two-dimensional systems.

Constructing the minimal model with deconfined fermions coupled to topological orders of the toric

code, spectral weights of physical fermions are perturbatively calculated. Characteristic evolutions

of the spectral gap under the fluctuations are demonstrated. Applying our results to experiments,

we provide a plausible scenario of thermal phase transitions without symmetry breaking, which may

be applied to the recent experiments in Sr2VO3FeAs.