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NEW: Colloquium Néel

Jean-François ROCH
Laboratoire Lumière, Matière et Interfaces – ENS Paris-Saclay, France

Thursday, May 27th at 9:30 am

Visio link: https://smartvisio2.neel.cnrs.fr/b/flo-vfn-qvm

Title: Magnetometry with NV color centers in diamond and its application to high-pressure physics

Abstract: The nitrogen-vacancy (NV) color center is a point defect of diamond that behaves as an artificial atom with a discrete spectrum of quantum states. Due to this remarkable property, the NV center can be used as a magnetic field, pressure, and temperature solid-state quantum sensor down to the atomic scale. I will present a brief state-of-the-art of optical magnetometry techniques that are based on the response of the NV center to the stray magnetic field that is created by a magnetized structure. I will also describe the Equipex+ project « e-DIAMANT » aimed to develop quantum-grade diamond.

I will then describe how this sensing technique can be implemented inside a diamond anvil cell in order to investigate the magnetic and superconducting properties of high-pressure materials. Indeed, the diamond anvil cell is a table-top system that implements in laboratory conditions pressures above the megabar range, leading to the onset of specific quantum states of matter. However, confining the sample in the tiny dimension of the diamond anvil cell makes the implementation of any non-optical sensing technique highly challenging. I will describe the results obtained on model phase transitions  induced by applying a pressure between 10 and 40 GPa inside a diamond anvil cell. This NV-based high-pressure sensing method is compatible with synchrotron-based characterization of the crystalline structure. The implementation of these complementary techniques in a single set-up opens a broad range of applications, for instance for the discovery of novel high-pressure superconductors.