title: Optical absorption to probe the quantum Hall ferromagnet at filling factor nu=1.
abstract: Optical absorption measurements are used to probe the spin polarization in the integer and fractional quantum Hall effect regimes. The system is fully spin polarized only at filling factor nu=1 and at very low temperatures ( approximately 40 mK). A small change in filling factor (deltanu approximately +/-0.01) leads to a significant depolarization. This suggests that the itinerant quantum Hall ferromagnet at nu=1 is surprisingly fragile against increasing temperature, or against small changes in filling factor.
authors.affiliation: Laboratoire National des Champs Magnétiques Intenses, Grenoble High Magnetic Field Laboratory, 38042 Grenoble, France. Paulina.Plochocka@grenoble.cnrs.fr
authors.forename: P
authors.initials: P
authors.lastname: Plochocka
authors.forename: J M
authors.initials: JM
authors.lastname: Schneider
authors.forename: D K
authors.initials: DK
authors.lastname: Maude
authors.forename: M
authors.initials: M
authors.lastname: Potemski
authors.forename: M
authors.initials: M
authors.lastname: Rappaport
authors.forename: V
authors.initials: V
authors.lastname: Umansky
authors.forename: I
authors.initials: I
authors.lastname: Bar-Joseph
authors.forename: J G
authors.initials: JG
authors.lastname: Groshaus
authors.forename: Y
authors.initials: Y
authors.lastname: Gallais
authors.forename: A
authors.initials: A
authors.lastname: Pinczuk