# Quantum sensing of local magnetic field texture in strongly correlated electron systems under extreme conditions

## TL;DR

This paper demonstrates the use of nitrogen vacancy centers in diamond as a sensitive, spatially-resolved magnetic field sensor for studying pressure-induced phenomena in strongly correlated electron systems at cryogenic temperatures.

## Contribution

It introduces a novel method for magnetic field sensing under high pressure using NV centers, enabling detailed studies of quantum many-body systems.

## Key findings

- Successfully measured superconducting transition temperature (Tc)
- Mapped local magnetic field profiles in the Meissner state
- Determined critical magnetic fields Hc1 and Hc2

## Abstract

An important feature of strong correlated electron systems is the tunability between interesting ground states such as unconventional superconductivity and exotic magnetism. Pressure is a clean, continuous and systematic tuning parameter. However, due to the restricted accessibility introduced by high-pressure devices, compatible magnetic field sensors with sufficient sensitivity are rare. This greatly limits the detections and detailed studies of pressure-induced phenomena. Here, we utilize nitrogen vacancy (NV) centers in diamond as a powerful, spatially-resolved vector field sensor for material research under pressure at cryogenic temperatures. Using a single crystal of BaFe2(As0:59P0:41)2 as an example, we extract the superconducting transition temperature (Tc), the local magnetic field profile in the Meissner state and the critical fields (Hc1 and Hc2). The method developed in this work will become a unique tool for tuning, probing and understanding quantum many body systems.