Magneto-optical measurements on niobium selenide, barium fluoride and gallium arsenide
MetadataShow full item record
The magneto-optical properties of NbSe 2 , BaF 2 and GaAs were studied in the 100-1000meV energy range. NbSe 2 is layered structure, which undergoes a charge density wave (CDW) and a superconducting transition. There is a competition between this two order parameters. I developed methods to prepare a NbSe 2 sample for Faraday and Kerr measurements. Furthermore I calculated the Faraday and Kerr angle we should obtain if we model the sample as a metal. Using published reflectance data , I determined the complex conductivity of NbSe 2 . The conductivity was used to determine the transmittance of NbSe 2 as a function of thickness and predicted the Faraday and Kerr signals that we can expect if we model NbSe 2 as a simple Drude metal. The result of our measurements gives us an upper limit of the Kerr angle of about [straight theta] K [approximate] 5 · [Special characters omitted.] <math> <f> 10<sup>-5<fr><nu>rad</nu><de>T</de></fr></sup></f> </math> . I also investigated experimental ways making NbSe 2 thin enough getting sufficient amount of light through to measure the Faraday angle. For 100 nm films I calculated T [approximate] 0.2%. The response of GaAs and BaF 2 is also important for us since these materials are used as substrates and windows in our measurements of materials like NbSe, Ca x Sr 1-x RuO 3 and dilute magnetic semiconductors in general. Since we confirmed the ∝ [Special characters omitted.] <math> <f> <hsp sp="0.265"><fr><nu>1</nu><de><g>l</g><sup>2</sup></de></fr> </f> </math> behavior of the Verdet constant this measurements give us the possibility to subtract the background signals accurately. Also we can test the absolute accuracy of our measurements, since the response of GaAs is well known. This is especially important for the current NbSe 2 measurement since this signals are very weak.