title: Composite-fermion spin excitations as nu approaches 1/2: interactions in the Fermi sea.
abstract: Measurements of low-lying spin excitations by inelastic light scattering unveil a delicate balance between spin reversal and Fermi energies in the Fermi sea of composite fermions that emerges in the limit of nu --> 1/2. The interplays between these two fundamental quasiparticle interactions are uncovered in lowest spin-flip excitations in which the spin orientation and Landau level index of composite fermions change simultaneously. A collapse of the spin-flip excitation gap as nu --> 1/2 is linked to vanishing quasiparticle energy level spacings and loss of full spin polarization.
authors.affiliation: Department of Applied Physics and Applied Math, Columbia University, New York, New York 10027, USA.
authors.forename: Irene
authors.initials: I
authors.lastname: Dujovne
authors.forename: A
authors.initials: A
authors.lastname: Pinczuk
authors.forename: Moonsoo
authors.initials: M
authors.lastname: Kang
authors.forename: B S
authors.initials: BS
authors.lastname: Dennis
authors.forename: L N
authors.initials: LN
authors.lastname: Pfeiffer
authors.forename: K W
authors.initials: KW
authors.lastname: West