A quantum critical point lying beneath the superconducting dome in iron pnictides

Abstract

Whether a quantum critical point (QCP) lies beneath the superconducting dome has been a long-standing issue that remains unresolved in many classes of unconventional superconductors, notably cuprates, heavy fermions, and, most recently, iron pnictides. The existence of a QCP may offer a route to understanding the origin of unconventional superconductors' anomalous non-Fermi liquid properties, the microscopic coexistence between unconventional superconductivity and magnetic or some other exotic order, and, ultimately, the mechanism of superconductivity itself. The isovalent substituted iron pnictide BaFe2(As1-xPx)2offers a new platform for the study of quantum criticality, providing a unique opportunity to study the evolution of the electronic properties in a wide range of the phase diagram. Recent experiments in BaFe2(As1-xPx)2have provided the first clear and unambiguous evidence of a second-order quantum phase transition lying beneath the superconducting dome. © Copyright 2014 by Annual Reviews. All rights reserved.