A Holographic Quantum Critical Point at Finite Magnetic Field and Finite Density

TL;DR

This paper explores a holographic model of N=4 supersymmetric Yang-Mills theory revealing a quantum critical point at finite magnetic field and density, with second-order phase transition characteristics and signatures of new phases.

Contribution

It identifies a generic holographic quantum critical point at finite magnetic field and density, characterizing its properties and phase transition behavior.

Findings

Discovery of an isolated quantum critical point separating different density phases.

Characterization of the critical point as a second-order transition with mean-field exponents.

Observation of signatures indicating a new phase dominated by the critical point.

Abstract

We analyze the phase diagram of N=4 supersymmetric Yang-Mills theory with fundamental matter in the presence of a background magnetic field and nonzero baryon number. We identify an isolated quantum critical point separating two differently ordered finite density phases. The ingredients that give rise to this transition are generic in a holographic setup, leading us to conjecture that such critical points should be rather common. In this case, the quantum phase transition is second order with mean-field exponents. We characterize the neighborhood of the critical point at small temperatures and identify some signatures of a new phase dominated by the critical point. We also identify the line of transitions between the finite density and zero density phases. The line is completely determined by the mass of the lightest charged quasiparticle at zero density. Finally, we measure the magnetic susceptibility and find hints of fermion condensation at large magnetic field.