An adaptive algorithm for n-body field expansions
Weinberg, Martin D.
1998-05-28
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35 records were found.
Comment: 20 pages, 11 figures, 1 table; v2: explanation added in section 2,
some minor changes
Comment: 4 pages, 3 figures. to appear in Phys. Rev. Lett
Colossal negative magnetoresistance and the associated field-induced
insulator-to-metal transition, the most characteristic features of magnetic
semiconductors, are observed in n-type rare earth oxides and chalcogenides,
p-type manganites, n-type and p-type diluted magnetic semiconductors (DMS) as
well as in quantum wells of n-type DMS. Here, we report on magnetostransport
studies of Mn modulation-doped InAs quantum wells, which reveal a magnetic
field driven and bias voltage dependent insulator-to-metal transition with
abrupt and hysteretic changes of resistance over several orders of magnitude.
These phenomena coexist with the quantised Hall effect in high magnetic fields.
We show that the exchange coupling between a hole and the parent Mn acceptor
produces a magnetic anisotropy barrier that shifts the spin relaxation time of
the b...
Comment: 7 pages, including 4 figures Changes made to introduction Added
figure Submitted to SSC
Comment: 5 pages, 5 figures
Comment: 8 pages, 10 figures, 1 table
Measurements of elastic and inelastic cotunneling currents are presented on a
two-terminal Aharonov--Bohm interferometer with a Coulomb blockaded quantum dot
embedded in each arm. Coherent current contributions, even in magnetic field,
are found in the nonlinear regime of inelastic cotunneling at finite bias
voltage. The phase of the Aharonov--Bohm oscillations in the current exhibits
phase jumps of $\pi$ at the onsets of inelastic processes. We suggest that
additional coherent elastic processes occur via the excited state. Our
measurement technique allows the detection of such processes on a background of
other inelastic current contributions and contains information about the
excited state occupation probability and the inelastic relaxation rates.
Comment: 7 pages, 5 figures
Comment: Accepted for publication on Physical Review B Rapid Communications
