Experimental Setup Of Measuring The De Haas-van Alphen Effect And Its Applications In Correlated Materials

Fermi surface (FS) is a fundamental parameter in the momentum space which is useful for describing the physical properties of metallic compounds. However, determination of their Fermi surface topology is a challenge for many complex compounds.Quantum oscillations, e.g., the de Haas-van Alphen (dHvA) effect, provide a unique method for determining the bulk Fermi surface if highly pure samples are available. The dHvA effect is a quantum mechanical effect of electron motion in a magnetic field, reflecting on the oscillations of magnetic susceptibility as a function of magnetic field. It can be measured by a coil modulation as well as a torque method. In comparison with the coil modulation method, the torque method allows to measure tiny crystals with a high accuracy, which is particularly useful for some correlated materials because large crystals are not always available.In this thesis, we developed an experimental setup to measure the dHvA effect by using a torque method and applied this technique to determine the Fermi surface of the heavy fermion compound CeRhln5. The thesis is organized as follows:In chapter1, we firstly introduce the concept of FS and its relation to the physical properties. Then, different experimental techniques of measuring FS are compared. After that, a brief introduction to the heavy fermion compounds is presented.Chapter2is devoted to the design and test of the experimental setups for measuring the dHvA oscillations. Following a theoretical introduction of the dHvA effect and its relation with FS and cyclotron mass, we present a detailed description on the design of the experimental setup, the subsequent tests and various improvements.Chapter3applies the experimental measurements to the heavy fermion compound CeRhln5. It is found that our results are highly consistent with those reported in literature using a coil modulation method, confirming the validity of our experimental setup. Furthermore, in order to study the evolution of the dHvA frequencies as a function of magnetic field, the same sample was also measured in the National High Magnetic Field laboratory in US which is compared with the results measured by the method developed in this thesis.