Probing the Quantum Noise of the Spinon Fermi Surface with NV Centers

TL;DR

This paper investigates the magnetic noise generated by a U(1) spin liquid with a spinon Fermi surface, revealing its similarities to metallic behavior and estimating NV center coherence times for potential experimental detection.

Contribution

It provides a corrected theoretical analysis of the magnetic noise response in spin liquids and estimates experimental parameters for NV center detection.

Findings

Magnetic noise in spin liquids mimics metallic wave-vector dependence.

The response is scaled by a factor related to spinon and chargon susceptibilities.

Estimated NV center T1 times range from tens to hundreds of milliseconds.

Abstract

We study the transverse electrical conductivity and the corresponding magnetic noise of a two-dimensional U(1) spin liquid state with a spinon Fermi surface. We show that in the quasi-static regime these responses have the same wave-vector dependence as that of a metal but are reduced by a dimensionless pre-factor controlled by the ratio of orbital diamagnetic susceptibilities of the spinons and chargons, correcting previous work. We estimate that this quasi-static regime is comfortably accessed by the typical NV center splittings of a few GHz and estimate that the expected T1 times for an NV center placed above candidate materials, such as the organic dmit and ET salts, monolayer 1T-TaS2/Se2, would range from several tens to a few hundred milliseconds.