RESUMO
We present a new technique to measure pulsed magnetic fields based on the use of rubidium in gas phase as a metrological standard. We have therefore developed an instrument based on laser inducing transitions at about 780 nm (D2 line) in rubidium gas contained in a mini-cell of 3 mm × 3 mm cross section. To be able to insert such a cell in a standard high-field pulsed magnet, we have developed a fibred probe kept at a fixed temperature. Transition frequencies for both the π (light polarization parallel to the magnetic field) and σ (light polarization perpendicular to the magnetic field) configurations are measured by a commercial wavemeter. One innovation of our sensor is that in addition to the usual monitoring of the light transmitted by the Rb cell, we also monitor the fluorescence emission of the gas sample from a volume of 0.13 mm3. Our sensor has been tested up to about 58 T.
RESUMO
Cd(3)As(2) is a candidate three-dimensional Dirac semimetal which has exceedingly high mobility and nonsaturating linear magnetoresistance that may be relevant for future practical applications. We report magnetotransport and tunnel diode oscillation measurements on Cd(3)As(2), in magnetic fields up to 65 T and temperatures between 1.5 and 300 K. We find that the nonsaturating linear magnetoresistance persists up to 65 T and it is likely caused by disorder effects, as it scales with the high mobility rather than directly linked to Fermi surface changes even when approaching the quantum limit. From the observed quantum oscillations, we determine the bulk three-dimensional Fermi surface having signatures of Dirac behavior with a nontrivial Berry phase shift, very light effective quasiparticle masses, and clear deviations from the band-structure predictions. In very high fields we also detect signatures of large Zeeman spin splitting (gâ¼16).
