Graphene spin capacitor for magnetic field sensing

An analysis of a novel magnetic field sensor based on a graphene spin capacitor is presented. The proposed device consists of graphene nanoribbons on top of an insulator material connected to a ferromagnetic source/drain. The time evolution of spin polarized electrons injected into the capacitor can be used for an accurate determination at room temperature of external magnetic fields. Assuming a spin relaxation time of 100 ns, magnetic fields on the order of $\sim 10$ mOe may be detected at room temperature. The observational accuracy of this device depends on the density of magnetic defects and spin relaxation time that can be achieved.Comment: 6 pages, 3 figure

Cavity flow with surface tension past a flat plate

The effect of surface tension forces on the cavity flow parameters is considered for steady flow past a rounded-edge plate perpendicular to the incident flow. The fluid is assumed to be ideal, weightless, and incompressible. The problem is solved in a parameter region by finding analytical expressions for the flow potential and the function that conformally maps the parameter region into the flow region in the physical plane. The dynamic boundary condition includes the surface tension force, which is proportional to the free boundary curvature, and allows one to obtain an integral equation in the velocity magnitude on the free boundary. The integral equation is solved numerically by the method of successive approximations. The results of calculations of the effect of the Weber number and the plate edge radius on the geometry of the cavity and the drag coefficient of the plate are presented.http://deepblue.lib.umich.edu/bitstream/2027.42/84246/1/CAV2009-final48.pd

Bistability in a magnetic and nonmagnetic double-quantum-well structure mediated by the magnetic phase transition

The hole distribution in a double quantum well (QW) structure consisting of a magnetic and a nonmagnetic semiconductor QW is investigated as a function of temperature, the energy shift between the QWs, and other relevant parameters. When the itinerant holes mediate the ferromagnetic ordering, it is shown that a bistable state can be formed through hole redistribution, resulting in a significant change in the properties of the constituting magnetic QW (i.e., the paramagnetic-ferromagnetic transition). The model calculation also indicates a large window in the system parameter space where the bistability is possible. Hence, this structure could form the basis of a stable memory element that may be scaled down to a few hole regime.Comment: 9 pages, 3 figure