Effects of intermediate magnetic fields on charge order in YBCO

Several theoretical proposals suggest that the microscopic origin of the superconductivity in high Tc cuprate superconductors might reside in the modulations of the electron density. However, charge density waves (CDW) demonstrated over years a clear competition with the superconductivity: they weaken below Tc and are enhanced by magnetic fields. The recently discovered charge density fluctuations (CDF) might instead represent the long-sought excitations, since their signal is not reduced below Tc. Here, we propose to study in YBa2Cu3O7-δ films the response of CDW and CDF to magnetic fields of the order of 1 T, which we will achieve using an optimized geometry with two permanent magnets and a concentrator, and that we already tested to induce a significant variation in the charge order signal. Depending if CDW and CDF behave differently or not, we will be able to say if they have a common nature or instead if CDF might be regarded as a possible candidate to drive the pairing.