10,538 research outputs found
Flux Line Lattice Melting and the Formation of a Coherent Quasiparticle Bloch State in the Ultraclean URuSi Superconductor
We find that in ultraclean heavy-fermion superconductor URuSi
( K) a distinct flux line lattice melting transition with
outstanding characters occurs well below the mean-field upper critical fields.
We show that a very small number of carriers with heavy mass in this system
results in exceptionally large thermal fluctuations even at subkelvin
temperatures, which are witnessed by a sizable region of the flux line liquid
phase. The uniqueness is further highlighted by an enhancement of the
quasiparticle mean free path below the melting transition, implying a possible
formation of a quasiparticle Bloch state in the periodic flux line lattice.Comment: 5 pages, 4 figures, accepted for publication in Phys. Rev. Let
Ultrahigh-Field Hole Cyclotron Resonance Absorption in InMnAs Films
We have carried out an ultrahigh-field cyclotron resonance study of p-type
In1-xMnxAs films, with Mn composition x ranging from 0% to 2.5%, grown on GaAs
by low-temperature molecular-beam epitaxy. Pulsed magnetic fields up to 500 T
were used to make cyclotron resonance observable in these low-mobility samples.
The clear observation of hole cyclotron resonance is direct evidence of the
existence of a large number of itinerant, effective-mass-type holes rather than
localized d-like holes. It further suggests that the p-d exchange mechanism is
more favorable than the double exchange mechanism in this narrow gap InAs-based
dilute magnetic semiconductor. In addition to the fundamental heavy-hole and
light-hole cyclotron resonance absorption appearing near the
high-magnetic-field quantum limit, we observed many inter-Landau-level
absorption bands whose transition probabilities are stronglydependent on the
sense of circular polarization of the incident light.Comment: 8 pages, 10 Postscript figure
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