Perturbing orbital molecule orders

The aim of my project is to study double double perovskites, which have the general formula AA'BB'O6. The perovskite structure is very flexible. It can accommodate many different cations on the A and B sites and thus displays a wide range of magnetic properties and allows for their tuning. The ordered double double perovskites are more difficult to synthesise than simple and double perovskites with the formula ABO3 or AA'B2O6/A2BB'O6.Indeed, high pressure and high temperature are required to successfully synthesise pure samples due to the fact that these phases are not accessible at ambient pressure and temperature. The syntheses are performed in a Walker-type multi-anvil press equipped with a heating rack, that can apply a pressure of 20 GPa and reach temperatures up to 1500 C. The obtained samples are analysed using a laboratory x-ray diffractometer for phase identification. The eventual presence of impurities is used to finely tune the synthesis conditions. When the samples are pure, the magnetic properties can be explored. Magnetic measurements are carried out using a SQUID magnetometer, to measure the temperature dependence of the magnetic susceptibility and M(H) hysteresis loops. Analysis of the measurements allows the extraction of characteristic parameters: transition temperatures and magnetic moments to name a couple. The magnetic and nuclear structure can be studied with neutron diffraction experiments performed at large scale facilities, such as ISIS and ILL through a proposal system.