title: Spontaneous breaking of time-reversal symmetry in strongly interacting two-dimensional electron layers in silicon and germanium.
abstract: We report experimental evidence of a remarkable spontaneous time-reversal symmetry breaking in two-dimensional electron systems formed by atomically confined doping of phosphorus (P) atoms inside bulk crystalline silicon (Si) and germanium (Ge). Weak localization corrections to the conductivity and the universal conductance fluctuations were both found to decrease rapidly with decreasing doping in the Si:P and Ge:P delta layers, suggesting an effect driven by Coulomb interactions. In-plane magnetotransport measurements indicate the presence of intrinsic local spin fluctuations at low doping, providing a microscopic mechanism for spontaneous lifting of the time-reversal symmetry. Our experiments suggest the emergence of a new many-body quantum state when two-dimensional electrons are confined to narrow half-filled impurity bands.
authors: Department of Physics, Indian Institute of Science, Bangalore 560 012, India.
authors: S
authors: S
authors: Shamim
authors: Centre for Quantum Computation and Communication Technology, University of New South Wales, Sydney, New South Wales 2052, Australia.
authors: S
authors: S
authors: Mahapatra
authors: Centre for Quantum Computation and Communication Technology, University of New South Wales, Sydney, New South Wales 2052, Australia.
authors: G
authors: G
authors: Scappucci
authors: Centre for Quantum Computation and Communication Technology, University of New South Wales, Sydney, New South Wales 2052, Australia.
authors: W M
authors: WM
authors: Klesse
authors: Centre for Quantum Computation and Communication Technology, University of New South Wales, Sydney, New South Wales 2052, Australia.
authors: M Y
authors: MY
authors: Simmons
authors: Department of Physics, Indian Institute of Science, Bangalore 560 012, India.
authors: A
authors: A
authors: Ghosh
mesh_terms: D004553:Electric Conductivity; D004583:Electrons; D005857:Germanium / Q000737:chemistry*; D008956:Models, Chemical; D010758:Phosphorus / Q000737:chemistry; D011789:Quantum Theory; D012825:Silicon / Q000737:chemistry*
chemical_list: D005857:Germanium; D010758:Phosphorus; D012825:Silicon