Laboratoire Charles Coulomb UMR 5221 CNRS/UM2 (L2C)


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Spin Noise spectroscopy and Nuclear spin

par PEPS - publié le , mis à jour le

Spin noise spectroscopy (SNS) is a powerful new method for studying magnetic resonance and spin dynamics. It is based on measuring magnetization noise of a paramagnet using the Faraday rotation technique. We have contributed to the development of this technique, by increasing both its sensitivity and accessible frequency range using heterodyne detection scheme [Cronenberger2016]. The SNS implemented in L2C allowed, in particular, for the detection of atomic-like spin fluctuations of Mn ions diluted in CdTe, while previously SNS was limited to carriers in semiconductor heterostructures [Cronenberger2015]. More recently we implemented spatiotemporal spin noise spectroscopy and applied it to n-CdTe, reaching spatial resolutions down to ∼λ/10 [Cronenberger2019,Cronenberger2021]. This activity benefits from long-standing fruitful collaboration with institute Néel.

In a set of theoretical and experimental works we have established the potential of the SNS for probing nuclear spin polaron, a collective electron-nuclei spin state which is specific to semiconductors [Vladimirova2021]. To do so, we have addressed experimentally and theoretically nuclear spin relaxation in both n and p-type GaAs, as a function of impurity concentration and magnetic field (collaboration with C2N and SpinOptics Lab in St-Petersburg). The adiabatic demagnetization of nuclei to zero magnetic field, detected by SNS, provided us with a first direct confirmation of the nuclear spin temperature hypothesis, and a direct measurement of the nuclear heat capacity field [Vladimirova2018]. Later on we proposed and implemented nuclear magnetic resonance experiments detected by electron spin noise. These experiments allowed us to establish a connection between the residual strain in n-GaAs giving rise to quadrupole splittings, the increased heat capacity and nuclear spin relaxation rates at low and zero field [Vladimirova2021].

This topic has been initially developed in the framework ANR SNS and PRC Russie SpinCool. It is now supported by ANR-RNF CONUS : COrrelated NUclear Spin states in n-GaAs and nanostructures.

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