Hall-effect (HE) sensors based on high-quality Mn-doped Bi2Te3 topological insulator (TI) thin films have been systematically studied in this paper. Improvement of Hall sensitivity is found after doping the magnetic element Mn into Bi2Te3. The sensors with low Mn concentrations, MnxBi2-xTe3, x = 0.01 and 0.08 show the linear behavior of Hall resistance with sensitivity about 5 Ω/T. And their Ha...

[1] To understand the role of the Hall effect during fast magnetic reconnection, hybrid simulations with and without the Hall term in the generalized Ohm’s Law are compared, as done originally by Karimabadi et al. (2004). It is found that reconnection with the Hall term is fast, but reconnection in the so-called Hall-less hybrid simulations is Sweet-Parker like (slow) when the resistivity is co...

We measure the longitudinal conductivity σxx at frequencies 1.246 GHz ≤ f ≤ 10.05 GHz over a range of temperatures 235 mK ≤ T ≤ 4.2 K with particular emphasis on the Quantum Hall plateaus. We find that Re(σxx) scales linearly with frequency for a range of magnetic field around the center of the plateaus, i.e. where σxx(ω) ≫ σ DC xx . The width of this scaling region decreases with higher temper...

We report on magnetotransport measurements of multiterminal suspended graphene devices. Fully developed integer quantum Hall states appear in magnetic fields as low as 2 T. At higher fields the formation of longitudinal resistance minima and transverse resistance plateaus are seen corresponding to fractional quantum Hall states, most strongly for 1⁄4 1=3. By measuring the temperature dependence...

We propose the two formalisms for obtaining the noncommutative spacetime in a magnetic field. One is the first-order formalism and the other is the second-order formalism. Although the noncommutative spacetime is realized manifestly in the first-order formalism, the second-order formalism would be more useful for calculating the physical quantities in the noncommutative geometry than the first-...

We consider magnetotransport in a disordered two-dimensional electron gas in the presence of a periodic modulation in one direction. First we review both quasiclassical and quantum approaches to this problem. These approaches account for Weiss oscillations in the resistivity tensor at moderate magnetic fields, as well as a strong modulation-induced modification of the Shubnikovde Haas oscillati...

This paper addresses the question of how current is distributed within quantum Hall effect devices. Three types of flow patterns most often mentioned in the literature are considered. They are: (1) skipping orbits along the device periphery (which arise from elastic collisions off hard-walled potentials); (2) narrow conducting channels along the device sides (which are presumed to be generated ...

As semiconductor electronics push up against the limits of Moore’s law, physicists are seeking new ways to manipulate and store information in matter. A promising new direction is “spintronics” [1], a kind of electronics built around the spin carried by electrons, rather than the charge. Spin is the basis of ferromagnets, which are magnets in which the electron spins are aligned. The informatio...

We discuss the anomalous Hall effect in a two-dimensional electron gas subject to a spatially varying magnetization. This topological Hall effect does not require any spin-orbit coupling and arises solely from Berry phase acquired by an electron moving in a smoothly varying magnetization. We propose an experiment with a structure containing 2D electrons or holes of diluted magnetic semiconducto...

Certain magnetic recording applications call for a large number of sequences whose differences do not include certain disallowed binary patterns. We show that the number of such sequences increases exponentially with their length and that the growth rate, or capacity, is the logarithm of the joint spectral radius of an appropriately defined set of matrices. We derive a new algorithm for determi...