The Collapse of the Spin-Singlet Phase in Quantum Dots

M. Ciorga, A. Wensauer, M. Pioro-Ladriere, M. Korkusinski, Jordan Kyriakidis, A. S. Sachrajda, P. Hawrylak

Published 2001-10-11, updated 2002-03-28Version 2

We present experimental and theoretical results on a new regime in quantum dots in which the filling factor 2 singlet state is replaced by new spin polarized phases. We make use of spin blockade spectroscopy to identify the transition to this new regime as a function of the number of electrons. The key experimental observation is a reversal of the phase in the systematic oscillation of the amplitude of Coulomb blockade peaks as the number of electrons is increased above a critical number. It is found theoretically that correlations are crucial to the existence of the new phases.