681 research outputs found
Tuning alloy disorder in diluted magnetic semiconductors in high fields to 89 T
Alloy disorder in II-VI diluted magnetic semiconductors (DMS) is typically
reduced when the local magnetic spins align in an applied magnetic field. An
important and untested expectation of current models of alloy disorder,
however, is that alloy fluctuations in many DMS compounds should increase again
in very large magnetic fields of order 100 tesla. Here we measure the disorder
potential in a ZnCdMnSe quantum well via the low
temperature photoluminescence linewidth, using a new magnet system to 89 T.
Above 70 T, the linewidth is observed to increase again, in accord with a
simple model of alloy disorder.Comment: 4 pages, 3 figure
Low temperature terahertz spectroscopy of n-InSb through a magnetic field driven metal-insulator transition
We use fiber-coupled photoconductive emitters and detectors to perform
terahertz (THz) spectroscopy of lightly-doped n-InSb directly in the cryogenic
(1.5 K) bore of a high-field superconducting magnet. We measure transmission
spectra from 0.1-1.1 THz as the sample is driven through a metal-insulator
transition (MIT) by applied magnetic field. In the low-field metallic state,
the data directly reveal the plasma edge and magneto-plasmon modes. With
increasing field, a surprisingly broad band (0.3-0.8 THz) of low transmission
appears at the onset of the MIT. This band subsequently collapses and evolves
into the sharp 1s -> 2p- transition of electrons `frozen' onto isolated donors
in the insulating state.Comment: 4 pages, 3 figure
Suprathermal electron isotropy in high-beta solar wind and its role in heat flux dropouts
[1] Time variations in plasma beta and a parameter which measures isotropy in suprathermal electron pitch angle distributions show a remarkably close correspondence throughout the solar wind. The finding implies that high-beta plasma, with its multiple magnetic holes and sharp field and plasma gradients, is conducive to electron pitch-angle scattering, which reduces heat flux from the Sun without field-line disconnection. Thus the finding impacts our understanding of signatures we use to determine magnetic topology in the heliosphere
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