Latest Research Papers In Condensed Matter Physics | (Cond-Mat.Mes-Hall) 2019-05-09
Mesoscale And Nanoscale Physics
Diverse quantization phenomena in layered materials (1905.03220v1)
Chiun-Yan Lin, Thi-Nga Do, Jhao-Ying Wu, Po-Hsin Shih, Shih-Yang Lin, Ching-Hong Ho, Ming-Fa Lin
2019-05-08
The diverse quantization phenomena in 2D condensed-matter systems, being due to a uniform perpendicular magnetic field and the geometry-created lattice symmetries, are the focuses of this book. They cover the diversified magneto-electronic properties, the various magneto-optical selection rules, the unusual quantum Hall conductivities, and the single- and many-particle magneto-Coulomb excitations. The rich and unique behaviors are clearly revealed in few-layer graphene systems with the distinct stacking configurations, the stacking-modulated structures, and the silicon-doped lattices, bilayer silicene/germanene systems with the bottom-top and bottom-bottom buckling structures, monolayer and bilayer phosphorene systems, and quantum topological insulators. The generalized tight-binding model, the static and dynamic Kubo formulas, and the random-phase approximation, are developed/modified to thoroughly explore the fundamental properties and propose the concise physical pictures. The different high-resolution experimental measurements are discussed in detail, and they are consistent with the theoretical predictions.
Properties of Coupled Single-Electron Lines (1904.06822v2)
Krzysztof Pomorski, Panagiotis Giounanlis, Elena Blokhina, Andrew Mitchell, Imran Bashir, Dirk Leipold, Robert Bogdan Staszewski
2019-04-15
Fundamental properties of two electrostatically interacting single-electron lines (SEL) are determined from a minimalistic tight-binding model. The lines are represented by a chain of coupled quantum wells that could be implemented in a mainstream nanoscale CMOS process technology and tuned electrostatically by DC or AC voltage biases. The obtained results show an essential qualitative difference with two capacitively coupled classical electrical lines. The derived equations and their solutions prove that the two coupled SET lines can create an entanglement between electrons. The results indicate a possibility of constructing electrostatic (non-spin) coupled qubits that could be used as building blocks in a CMOS quantum computer.
Effect of defect-induced cooling on graphene hot-electron bolometers (1905.03199v1)
Abdel El Fatimy, Peize Han, Nicholas Quirk, Luke St. Marie, Matthew T. Dejarld, Rachael L. Myers-Ward, Kevin Daniels, Shojan Pavunny, D. Kurt Gaskill, Yigit Aytac, Thomas E. Murphy, Paola Barbara
2019-05-08
At high phonon temperature, defect-mediated electron-phonon collisions (supercollisions) in graphene allow for larger energy transfer and faster cooling of hot electrons than the normal, momentum-conserving electron-phonon collisions. Disorder also affects the heat flow between electrons and phonons at very low phonon temperature, where the phonon wavelength exceeds the mean free path. In both cases, the cooling rate is predicted to exhibit a characteristic cubic power law dependence on the electron temperature, markedly different from the T^4 dependence predicted for pristine graphene. The impact of defect-induced cooling on the performance of optoelectronic devices is still largely unexplored. Here we study the cooling mechanism of hot-electron bolometers based on epitaxial graphene quantum dots where the defect density can be controlled with the fabrication process. The devices with high defect density exhibit the cubic power law. Defect-induced cooling yields a slower increase of the thermal conductance with increasing temperature, thereby greatly enhancing the device responsivity compared to devices with lower defect density and operating with normal-collision cooling.
Study of edge states and conductivity in spin-orbit coupled bilayer graphene (1905.03167v1)
Priyanka Sinha, Saurabh Basu
2019-05-08
We present an elaborate and systematic study of the conductance properties of a zigzag bilayer graphene nanoribbon modeled by a Kane-Mele (KM) Hamiltonian. The interplay of the Rashba and the intrinsic spin-orbit couplings with the edge states, electronic band structures, charge and spin transport are explored in details. We have analytically derived the conditions for the edge states for a bilayer KM nanoribbon and show how these modes decay for lattice sites inside the bulk. It is particularly interesting to note that for a finite-size ribbon an even number of zigzag ribbon hosts a finite energy gap at the Dirac points, while the odd ones do not. This asymmetry is present both in presence and absence of a bias voltage that may exist between the layers. The interlayer Rashba spin-orbit coupling, along with the intralayer intrinsic spin-orbit and intralayer Rashba spin-orbit couplings seem to destroy the quantum spin Hall (QSH) phase where the QSH phase is identified by the presence of a conductance plateau (of magnitude 4e/h) in the vicinity of zero Fermi energy. The plateau is sensitive to the values of the spin-orbit coupling parameters. Further, the spin polarized conductance data reveal that a bilayer KM ribbon is found to be more efficient for spintronic applications compared to a monolayer graphene. Finally, a quick check with experiments is done via computing the effective mass of electrons.
Spin-valley Hall transport induced by spontaneous symmetry breaking in half-filled zero Landau level of bilayer graphene (1905.03166v1)
Miuko Tanaka, Yuya Shimazaki, Ivan Valerievich Borzenets, Kenji Watanabe, Takashi Taniguchi, Seigo Tarucha, Michihisa Yamamoto
2019-05-08
Intrinsic Hall conductivity, emerging when chiral symmetry is broken, is at the heart of future low energy consumption devices because it can generate non-dissipative charge neutral current. A symmetry breaking state is also induced by electronic correlation even for the centro-symmetric crystalline materials. However, generation of non-dissipative charge neutral current by intrinsic Hall conductivity induced by such spontaneous symmetry breaking is experimentally elusive. Here we report intrinsic Hall conductivity and generation of a non-dissipative charge neutral current in a spontaneous antiferromagnetic state of zero Landau level of bilayer graphene, where spin and valley contrasting Hall conductivity has been theoretically predicted. We performed nonlocal transport experiment and found cubic scaling relationship between the local and nonlocal resistance, as a striking evidence of the intrinsic Hall effect. Observation of such spontaneous Hall transport is a milestone toward understanding the electronic correlation effect on the non-dissipative transport. Our result also paves a way toward electrical generation of a spin current in non-magnetic graphene via coupling of spin and valley in this symmetry breaking state combined with the valley Hall effect.
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