2006 APS March Meeting
Monday–Friday, March 13–17, 2006;
Baltimore, MD
Session R2: Fractional Quantum Hall Systems
2:30 PM–5:30 PM,
Wednesday, March 15, 2006
Baltimore Convention Center
Room: Ballroom III
Sponsoring
Unit:
DCMP
Chair: Horst Stormer, Columbia University
Abstract ID: BAPS.2006.MAR.R2.1
Abstract: R2.00001 : New physics in the second Landau Level
2:30 PM–3:06 PM
Preview Abstract
Abstract
Author:
Gabor Csathy
(Princeton University)
Clean two-dimensional electron systems subjected to perpendicular
magnetic fields have a long history of revealing exotic ground
states. A large number of these states are only possible in the
presence of electron-electron interactions. Two notable examples
of such collective ground states are the fractional quantum Hall
liquids of the first two Landau levels and the electronic solids
called the stripe and bubble phases forming beyond the first
Landau level. These two classes of phases are simultaneously
present and hence compete in the second Landau level.
This talk will highlight our latest results on the evolution of
the states of the second Landau level as the magnetic field is
tilted away from the direction perpendicular to the sample. The
challenging task of cooling to millidegree temperatures and
in-situ tilting in this low temperature environment is achieved
with a hydraulically driven rotator equipped with sintered Silver
heat exchangers mounted onto the nuclear demagnetization stage of
a dilution refrigerator. We found that the bubble states are
rapidly destroyed with tilt and argue that such a behavior is
consistent with the formation of an electronic solid.
Furthermore, the well developed $\nu$ = 2+1/5 and 2+4/5 liquids
are found to be driven insulating while the 2+1/3 and 2+2/3
states survive to the largest tilt angles accessible. The
simplest interpretation of the rapid evolution of these states is
that bubble phases melt into a classical Hall gas and the $\nu$ =
2+1/5 and 2+4/5 liquids solidify with tilt. Our data suggest
that spin interaction plays an important role in the formation of
these phases. In particular, we surmise that the bubble phases
are not fully spin-polarized but most likely have a substantial
antiferromagnetic order. These bubble phases could be first
examples of antiferromagnetically ordered solids in a single
layer two-dimensional electron system.
This work was done in collaboration with J.S. Xia, C.L. Vicente,
E.D. Adams, N.S. Sullivan, D.C. Tsui, H.L. Stormer, L.N.
Pfeiffer, and K.W. West.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2006.MAR.R2.1