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We demonstrate that, in a quasi-two-dimensional electron system confined to an AlAs quantum well and occupying two conduction-band minima (valleys), a parallel magnetic field can couple to the electrons' orbital motion and tune the energies…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 T. Gokmen , Medini Padmanabhan , O. Gunawan , Y. P. Shkolnikov , K. Vakili , E. P. De Poortere , M. Shayegan

The valley splitting of the first few Landau levels is calculated as a function of the magnetic field for electrons confined in a strained silicon quantum well grown on a tilted SiGe substrate, using a parameterized tight-binding method.…

Materials Science · Physics 2009-11-11 Seungwon Lee , Paul von Allmen

We report here a systematic study of the energy gaps at the odd-integer quantum Hall states $\nu=3$ and 5 under tilted magnetic (B) fields in a high quality Si two-dimensional electron system. Out of the coincidence region, the valley…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 K. Lai , W. Pan , D. C. Tsui , S. Lyon , M. Mühlberger , F. Schäffler

We have investigated the valley splitting of two-dimensional electrons in high quality Si/Si$_{1-x}$Ge$_x$ heterostructures under tilted magnetic fields. For all the samples in our study, the valley splitting at filling factor $\nu=3$…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 K. Lai , T. M. Lu , W. Pan , D. C. Tsui , S. Lyon , J. Liu , Y. H. Xie , M. Muhlberger , F. Schaffler

We have realized an AlAs two-dimensional electron system in which electrons occupy conduction-band valleys with different Fermi contours and effective masses. In the quantum Hall regime, we observe both resistivity spikes and persistent…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 K. Vakili , E. Tutuc , M. Shayegan

We show that in a very strong magnetic field $B$ electron-phonon interaction gives rise to a splitting of Landau levels of a 2D electron into a series of infinitely degenerate sublevels. We provide both qualitative and quantitative…

Mesoscale and Nanoscale Physics · Physics 2009-10-30 V. V. Cheianov , A. P. Dmitriev , V. Yu. Kachorovskii

We show that valley degeneracy in rotationally faulted multilayer graphene may be broken in the presence of a magnetic field and interlayer commensurations. This happens due to a simultaneous breaking of both time-reversal and inversion…

Mesoscale and Nanoscale Physics · Physics 2015-06-17 Hridis K Pal , E. J. Mele , M. Kindermann

We determine the energy splitting of the conduction-band valleys in two-dimensional electrons confined to low-disorder Si quantum wells. We probe the valley splitting dependence on both perpendicular magnetic field $B$ and Hall density by…

The lifting of the two-fold degeneracy of the conduction valleys in a strained silicon quantum well is critical for spin quantum computing. Here, we obtain an accurate measurement of the splitting of the valley states in the low-field…

The authors investigate the magnetic field dependence of the energy splitting between low-lying valley states for electrons in a Si/SiGe quantum well tilted with respect to the crystallographic axis. The presence of atomic steps at the…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 Mark Friesen , M. A. Eriksson , S. N. Coppersmith

In a multi-valley electronic band structure, lifting of the valley degeneracy is associated with rotational symmetry breaking in the electronic fluid, and may emerge through spontaneous symmetry breaking order, or through a large response…

Valleytronics is rapidly emerging as an exciting area of basic and applied research. In two dimensional systems, valley polarisation can dramatically modify physical properties through electron-electron interactions as demonstrated by such…

Physical properties reflecting valley asymmetry of Landau levels in a biased bilayer graphene under magnetic field are discussed. Within the $4-$band continuum model with Hartree-corrected self-consistent gap and finite damping factor we…

Mesoscale and Nanoscale Physics · Physics 2010-01-14 Masaaki Nakamura , Eduardo V. Castro , Balazs Dora

We report the detailed study of the influence of the spin and valley splittings on such physical observables of the two-dimensional disordered electron liquid as resistivity, spin and valley susceptibilities. We explain qualitatively the…

Mesoscale and Nanoscale Physics · Physics 2008-05-17 I. S. Burmistrov , N. M. Chtchelkatchev

We report novel manifestation of the valley splitting for the two valley electron system in (100) Si-inversion layers at low carrier density. We found that valley splitting causes almost 100% modulation of the Shubnikov de Haas oscillations…

Strongly Correlated Electrons · Physics 2007-05-23 V. M. Pudalov , A. Punnoose , G. Brunthaler , A. Prinz , G. Bauer

We present both the experimental and theoretical investigation of a non-trivial electron Landau levels shift in magnetic field in wide ~20 nm HgTe quantum wells: Landau levels split under magnetic fields but become degenerate again when…

Mesoscale and Nanoscale Physics · Physics 2018-10-17 A. A. Dobretsova , A. D. Chepelianskii , N. N. Mikhailov , Z. D. Kvon

The valley splitting, which lifts the degeneracy of the lowest two valley states in a SiO$_2$/(100)Si/SiO$_2$ quantum well is examined through transport measurements. We demonstrate that the valley splitting can be observed directly as a…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 K. Takashina , Y. Ono , A. Fujiwara , Y. Takahashi , Y. Hirayama

Measurements on a two-dimensional electron system confined to an AlAs quantum well reveal that for a given electron density the valley susceptibility, defined as the change in valley population difference per unit strain, is enhanced as the…

Mesoscale and Nanoscale Physics · Physics 2008-10-14 Medini Padmanabhan , T. Gokmen , M. Shayegan

In a number of widely-studied materials, such as Si, AlAs, Bi, graphene, MoS2, and many transition metal dichalcogenide monolayers, electrons acquire an additional, spin-like degree of freedom at the degenerate conduction band minima, also…

Mesoscale and Nanoscale Physics · Physics 2018-08-01 M. A. Mueed , Md. Shafayat Hossain , I. Jo , L. N. Pfeiffer , K. W. West , K. W. Baldwin , M. Shayegan

We report measurements of the spin susceptibility in dilute two-dimensional electrons confined to a 45$\AA$ wide AlAs quantum well. The electrons in this well occupy an out-of-plane conduction-band valley, rendering a system similar to…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 K. Vakili , Y. P. Shkolnikov , E. Tutuc , E. P. De Poortere , M. Shayegan
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