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The unique optical properties of graphene, with broadband absorption and ultrafast response, make it a critical component of optoelectronic and spintronic devices. Using time-resolved momentum microscopy with high data rate and high dynamic…

Interband optical transitions in graphene are subject to pseudospin selection rules. Impulsive excitation with linearly polarized light generates an anisotropic photocarrier occupation in momentum space that evolves at timescales shorter…

Mesoscale and Nanoscale Physics · Physics 2015-11-18 M. Trushin , A. Grupp , G. Soavi , A. Budweg , D. De Fazio , U. Sassi , A. Lombardo , A. C. Ferrari , W. Belzig , A. Leitenstorfer , D. Brida

Analogous to charge and spin, electrons in solids endows an additional degree of freedom: the valley pseudospin. Two-dimensional hexagonal materials such as graphene exhibit two valleys, labelled as $\mathbf{K}$ and $\mathbf{K}^{\prime}$.…

Mesoscale and Nanoscale Physics · Physics 2022-01-12 M. S. Mrudul , Gopal Dixit

We have investigated the role of pseudospin polarization in electron wave packet dynamics in pristine graphene and in a graphene antidot lattice subject to an external magnetic field. Employing a Green's function formalism, we show that the…

Mesoscale and Nanoscale Physics · Physics 2021-03-09 R. A. W. Ayyubi , N. J. M. Horing , K. Sabeeh

One of the intriguing characteristics of honeycomb lattices is the appearance of a pseudo-magnetic field as a result of mechanical deformation. In the case of graphene, the Landau quantization resulting from this pseudo-magnetic field has…

Spin manipulation is one of the most critical challenges to realize spin-based logic devices and spintronic circuits. Graphene has been heralded as an ideal material to achieve spin manipulation but so far new paradigms and demonstrators…

Mesoscale and Nanoscale Physics · Physics 2016-03-11 Dinh Van Tuan , Stephan Roche

Exploring the properties of strongly correlated systems through quantum simulation with photons, cold atoms or polaritons represents an active area of research. In fact, the latter permits to shed the light on the behavior of complex…

Mesoscale and Nanoscale Physics · Physics 2017-09-20 Dmitry R. Gulevich , Dmitry Yudin

Since graphene has no band gap, photoluminescence is not expected from relaxed charge carriers. We have, however, observed significant light emission from graphene under excitation by ultrashort (30-fs) laser pulses. Light emission was…

Mesoscale and Nanoscale Physics · Physics 2010-09-20 Chun Hung Lui , Kin Fai Mak , Jie Shan , Tony F. Heinz

The concept of pseudo-spin provides a general framework for describing physical systems featuring two-component spinors, including light polarization, sublattice degrees of freedom in bipartite lattices, and valley polarization in 2D…

Monolayer graphene with an energy gap presents a pseudospin symmetry broken ferromagnet with a perpendicular pseudomagnetization whose direction is switched by altering the type of doping between n and p. We demonstrate an electrical…

Mesoscale and Nanoscale Physics · Physics 2015-05-30 Leyla Majidi , Malek Zareyan

We investigate the photoconductivity of graphene within the relaxation time approximation. In presence of the inter-band transitions induced by the linearly polarized light the photoconductivity turns out to be highly anisotropic due to the…

Materials Science · Physics 2011-10-18 Maxim Trushin , John Schliemann

We experimentally demonstrate graphene-plasmon polariton excitation in a continuous graphene monolayer resting on a two-dimensional subwavelength silicon grating. The subwavelength silicon grating is fabricated by a nanosphere lithography…

The energy spectrum of planar polytype graphene-based superlattices has been investigated. It is shown that their energy spectrum undergoes pseudospin splitting due to the asymmetry of quantum wells forming the superlattice potential…

Mesoscale and Nanoscale Physics · Physics 2015-10-28 P. V. Ratnikov , A. P. Silin

In graphene, the pseudospin and the valley flavor arise as new types of quantum degrees of freedom due to the honeycomb lattice comprising two sublattices (A and B) and two inequivalent Dirac points (K and K') in the Brillouin zone,…

Mesoscale and Nanoscale Physics · Physics 2011-12-26 Changwon Park , Heejun Yang , Andrew J. Mayne , Gerald Dujardin , Sunae Seo , Young Kuk , Jisoon Ihm , Gunn Kim

The suite of highly confined polaritons supported by two-dimensional (2D) materials constitutes a versatile platform for nano-optics, offering the means to channel light on deep-subwavelength scales. Graphene, in particular, has attracted…

Mesoscale and Nanoscale Physics · Physics 2021-08-11 T. P. Rasmussen , P. A. D. Gonçalves , Sanshui Xiao , Sebastian Hofferberth , N. Asger Mortensen , Joel D. Cox

We directly measure the hole spin lifetime in ferromagnetic GaMnAs via time- and polarization-resolved spectroscopy. Below the Curie temperature Tc, an ultrafast photoexcitation with linearly-polarized light is shown to create a…

Materials Science · Physics 2015-04-10 Aaron Patz , Tianqi Li , Xinyu Liu , Jacek K. Furdyna , Ilias E. Perakis , Jigang Wang

Polaritons in metals, semimetals, semiconductors, and polar insulators, with their extreme confinement of electromagnetic energy, provide many promising opportunities for enhancing typically weak light-matter interactions such as multipolar…

Pseudospin, an additional degree of freedom inherent in graphene, plays a key role in understanding many fundamental phenomena such as the anomalous quantum Hall effect, electron chirality and Klein paradox. Unlike the electron spin, the…

Many of the properties of graphene are tied to its lattice structure, allowing for tuning of charge carrier dynamics through mechanical strain. The graphene electro-mechanical coupling yields very large pseudomagnetic fields for small…

Mesoscale and Nanoscale Physics · Physics 2016-01-06 Shuze Zhu , Joseph A. Stroscio , Teng Li

The observation of micron size spin relaxation makes graphene a promising material for applications in spintronics requiring long distance spin communication. However, spin dependent scatterings at the contact/graphene interfaces affect the…

Mesoscale and Nanoscale Physics · Physics 2017-11-02 Ahmet Avsar , Dmitrii Unuchek , Jiawei Liu , Oriol Lopez Sanchez , Kenji Watanabe , Takashi Taniguchi , Barbaros Ozyilmaz , Andras Kis
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