The specific heat jump at the superconducting transition and the quantum critical nature of the normal state of Pnictide superconductors

TL;DR

This paper links the specific heat jump at the superconducting transition in pnictides to quantum criticality, suggesting the normal state is a quantum critical metal with a pairing instability, consistent across various doping levels.

Contribution

It proposes a theoretical explanation connecting the specific heat behavior to quantum criticality in the normal state of pnictide superconductors.

Findings

Specific heat jump scales with T_c^3

Normal state exhibits quantum critical behavior

Supports pairing instability in quantum critical metals

Abstract

Recently it was discovered that the jump in the specific heat at the superconducting transition in pnictide superconductors is proportional to the superconducting transition temperature to the third power, with the superconducting transition temperature varying from 2 to 25 Kelvin including underdoped and overdoped cases. Relying on standard scaling notions for the thermodynamics of strongly interacting quantum critical states, it is pointed out that this behavior is consistent with a normal state that is a quantum critical metal undergoing a pairing instability.