Alexei O. Orlov

Bio: Alexei O. Orlov is an academic researcher from University of Notre Dame. The author has contributed to research in topics: Quantum dot cellular automaton & Coulomb blockade. The author has an hindex of 34, co-authored 191 publications receiving 5974 citations. Previous affiliations of Alexei O. Orlov include Russian Academy of Sciences & Technische Universität München.

Majority Logic Gate for Magnetic Quantum-Dot Cellular Automata

Abstract: We describe the operation of, and demonstrate logic functionality in, networks of physically coupled, nanometer-scale magnets designed for digital computation in magnetic quantum-dot cellular automata (MQCA) systems. MQCA offer low power dissipation and high integration density of functional elements and operate at room temperature. The basic MQCA logic gate, that is, the three-input majority logic gate, is demonstrated.

Digital logic gate using quantum-Dot cellular automata

Abstract: A functioning logic gate based on quantum-dot cellular automata is presented, where digital data are encoded in the positions of only two electrons. The logic gate consists of a cell, composed of four dots connected in a ring by tunnel junctions, and two single-dot electrometers. The device is operated by applying inputs to the gates of the cell. The logic AND and OR operations are verified using the electrometer outputs. Theoretical simulations of the logic gate output characteristics are in excellent agreement with experiment.

Realization of a Functional Cell for Quantum-Dot Cellular Automata

Abstract: This paper presents an experimental demonstration of a basic cell of the quantum-dot cellular automata, a transistorless approach to computation that addresses the issues of device density, interconnection, and power dissipation. The device under study was composed of four metal dots, connected with tunnel junctions and capacitors, and operated at <50 mK. Operation was evidenced by switching of a single electron between output dots controlled by a single electron switching in input dots, demonstrating a nonlinear, bistable response.

Electron transport in AlGaN–GaN heterostructures grown on 6H–SiC substrates

Abstract: We investigated two-dimensional electron transport in doped AlGaN–GaN heterostructures (with the electron sheet concentration ns≈1013 cm−2) grown on conducting 6H–SiC substrates in the temperature range T=0.3–300 K. The electron mobility in AlGaN–GaN heterostructures grown on SiC was higher than in those on sapphire substrates, especially at cryogenic temperatures. The highest measured Hall mobility at room temperature was μH=2019 cm2/V s. At low temperatures, the electron mobility increased approximately five times and saturated below 10 K at μH=10250 cm2/V s. The experimental results are compared with the electron mobility calculations accounting for various electron scattering mechanisms.

Molecular quantum cellular automata cells. Electric field driven switching of a silicon surface bound array of vertically oriented two-dot molecular quantum cellular automata.

Abstract: The amine functionality of the linker on the dinuclear complex [trans-Ru(dppm)(2)(Ctbd1;CFc)(NCCH(2)CH(2)NH(2))][PF(6)] reacts with Si-Cl bonds of a chlorinated, highly B doped Si (111) surface to yield Si-N surface-complex bonds. The surface bound complex is constrained to a near vertical orientation by the chain length of the linker as confirmed by variable angle XPS. Oxidation of the dinuclear complex with ferrocenium ion or electrochemically generates a stable, biased Fe(III)-Ru(II) mixed-valence complex on the surface. Characterization of the array of surface bound complexes with spectroscopic as well as electrochemical techniques confirms the presence of strongly bound, chemically robust, mixed-valence complexes. Capping the flat array of complexes with a minimally perturbing mercury electrode permits the equalization of the Fe and Ru energy wells by an applied electric field. The differential capacitance of oxidized and unoxidized bound complexes is compared as a function of voltage applied between the Hg gate and the Si. The results show that electron exchange between the Fe and Ru sites of the array of dinuclear mixed-valence complexes at energy equalization generates a fluctuating dipole that produces a maximum in the capacitance versus voltage curve for each complex-counterion combination present. Passage through the capacitance maximum corresponds to switching of the molecular quantum cellular automata (QCA) cell array by the electric field from the Fe(III)-Ru(II) configuration to the Fe(II)-Ru(III) configuration, thereby confirming that molecules possess an essential property necessary for their use as elements of a QCA device.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Two-dimensional electron gases induced by spontaneous and piezoelectric polarization charges in N- and Ga-face AlGaN/GaN heterostructures

Abstract: Carrier concentration profiles of two-dimensional electron gases are investigated in wurtzite, Ga-face AlxGa1−xN/GaN/AlxGa1−xN and N-face GaN/AlxGa1−xN/GaN heterostructures used for the fabrication of field effect transistors. Analysis of the measured electron distributions in heterostructures with AlGaN barrier layers of different Al concentrations (0.15

The emergence of spin electronics in data storage

Abstract: Electrons have a charge and a spin, but until recently these were considered separately. In classical electronics, charges are moved by electric fields to transmit information and are stored in a capacitor to save it. In magnetic recording, magnetic fields have been used to read or write the information stored on the magnetization, which 'measures' the local orientation of spins in ferromagnets. The picture started to change in 1988, when the discovery of giant magnetoresistance opened the way to efficient control of charge transport through magnetization. The recent expansion of hard-disk recording owes much to this development. We are starting to see a new paradigm where magnetization dynamics and charge currents act on each other in nanostructured artificial materials. Ultimately, 'spin currents' could even replace charge currents for the transfer and treatment of information, allowing faster, low-energy operations: spin electronics is on its way.

Engineering atomic and molecular nanostructures at surfaces

Abstract: The fabrication methods of the microelectronics industry have been refined to produce ever smaller devices, but will soon reach their fundamental limits. A promising alternative route to even smaller functional systems with nanometre dimensions is the autonomous ordering and assembly of atoms and molecules on atomically well-defined surfaces. This approach combines ease of fabrication with exquisite control over the shape, composition and mesoscale organization of the surface structures formed. Once the mechanisms controlling the self-ordering phenomena are fully understood, the self-assembly and growth processes can be steered to create a wide range of surface nanostructures from metallic, semiconducting and molecular materials.

Magnetic Domain-Wall Logic

Abstract: “Spintronics,” in which both the spin and charge of electrons are used for logic and memory operations, promises an alternate route to traditional semiconductor electronics. A complete logic architecture can be constructed, which uses planar magnetic wires that are less than a micrometer in width. Logical NOT, logical AND, signal fan-out, and signal cross-over elements each have a simple geometric design, and they can be integrated together into one circuit. An additional element for data input allows information to be written to domain-wall logic circuits.