4 research outputs found
Self-resonant Coil for Contactless Electrical Conductivity Measurement under Pulsed Ultra-high Magnetic Fields
In this study, we develop experimental apparatus for contactless electrical
conductivity measurements under pulsed high magnetic fields over 100 T using a
self-resonant-type high-frequency circuit. The resonant power spectra were
numerically analyzed, and the conducted simulations showed that the apparatus
is optimal for electrical conductivity measurements of materials with high
electrical conductivity. The newly developed instruments were applied to a
high-temperature cuprate superconductor LaSrCuO to show
conductivity changes in magnetic fields up to 102 T with a good signal-to-noise
ratio. The upper critical field was determined with high accuracy.Comment: 11 pages, 5 figure
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Proximity detector circuits: an attractive alternative to tunnel diode oscillators for contactless measurements in pulsed magnetic fields
A new radio frequency oscillator circuit based on a proximity detector integrated circuit is described as an alternative for the traditional tunnel diode oscillator used for pulsed magnetic field measurements at low temperatures. The new circuit has been successfully applied to measure the superconducting upper critical field in Ba{sub 0.55}K{sub 0.45}Fe{sub 2}As{sub 2} single crystfl.ls up to 60 T. The new circuit design avoids many of the problems associated with tunnel diode circuits while keeping the advantages of contact less measurements in pulsed magnets
The surface-state of the topological insulator BiSe revealed by cyclotron resonance
To date transport measurements of topological insulators have been dominated
by the conductivity of the bulk, leading to substantial difficulties in
resolving the properties of the surface. To this end, we use high magnetic
field, rf- and microwave-spectroscopy to selectively couple to the surface
conductivity of BiSe at high frequency. In the frequency range of a few
GHz we observe a crossover from quantum oscillations indicative of a small 3D
Fermi surface, to cyclotron resonance indicative of a 2D surface state
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Radio-frequency measurements of UNiX compounds (X= Al, Ga, Ge) in high magnetic fields
We performed radio-frequency (RF) skin-depth measurements of antiferromagnetic UNiX compounds (X=Al, Ga, Ge) in magnetic fields up to 60 T and at temperatures between 1.4 to {approx}60 K. Magnetic fields are applied along different crystallographic directions and RF penetration-depth was measured using a tunnel-diode oscillator (TDO) circuit. The sample is coupled to the inductive element of a TDO resonant tank circuit, and the shift in the resonant frequency {Delta}f of the circuit is measured. The UNiX compounds exhibit field-induced magnetic transitions at low temperatures, and those transitions are accompanied by a drastic change in {Delta}f. The results of our skin-depth measurements were compared with previously published B-T phase diagrams for these three compounds