A Dual Gate Spin Field Effect Transistor With Very Low Switching Voltage and Large ON-to-OFF Conductance Ratio

We propose and analyze a novel dual-gate Spin Field Effect Transistor (SpinFET) with half-metallic ferromagnetic source and drain contacts. The transistor has two gate pads that can be biased independently. It can be switched ON or OFF with a few mV change in the differential bias between the two pads, resulting in extremely low dynamic power dissipation during switching. The ratio of ON to OFF conductance remains fairly large (~ 60) up to a temperature of 10 K. This device also has excellent inverter characteristics, making it attractive for applications in low power and high density Boolean logic circuits

The Effect of Ramsauer Type Transmission Resonances on the Conductance Modulation of Spin Interferometers

We use a mean field approach to study the conductance modulation of gate controlled semiconductor spin interferometers based on the Rashba spin-orbit coupling effect. The conductance modulation is found to be mostly due to Ramsauer type transmission resonances rather than the Rashba effect in typical structures. This is because of significant reflections at the interferometer's contacts due to large potential barriers and effective mass mismatch between the contact material and the semiconductor. Thus, unless particular care is taken to eliminate these reflections, any observed conductance modulation of spin interferometers may have its origin in the Ramsauer resonances (which is unrelated to spin) rather than the Rashba effect.Comment: 3 figure

A spin field effect transistor for low leakage current

In a spin field effect transistor, a magnetic field is inevitably present in the channel because of the ferromagnetic source and drain contacts. This field causes random unwanted spin precession when carriers interact with non-magnetic impurities. The randomized spins lead to a large leakage current when the transistor is in the ``off''-state, resulting in significant standby power dissipation. We can counter this effect of the magnetic field by engineering the Dresselhaus spin-orbit interaction in the channel with a backgate. For realistic device parameters, a nearly perfect cancellation is possible, which should result in a low leakage current.Comment: To appear in Physica E. The revised version has additional material which addresses the issue of which way the contacts should be magnetized in a Spin Field Effect Transistor. This was neither addressed in the previous version, nor in the upcoming journal pape

A Digital Switch and Femto-Tesla Magnetic Field Sensor Based on Fano Resonance in a Spin Field Effect Transistor

We show that a Spin Field Effect Transistor, realized with a semiconductor quantum wire channel sandwiched between half-metallic ferromagnetic contacts, can have Fano resonances in the transmission spectrum. These resonances appear because the ferromagnets are half-metallic, so that the Fermi level can be placed above the majority but below the minority spin band. In that case, the majority spins will be propagating, but the minority spins will be evanescent. At low temperatures, the Fano resonances can be exploited to implement a digital binary switch that can be turned on or off with a very small gate voltage swing of few tens of microvolts, leading to extremely small dynamic power dissipation during switching. An array of 500,000 x 500,000 such transistors can detect ultrasmall changes in a magnetic field with a sensitivity of 1 femto-Tesla/sqrt{Hz}, if each transistor is biased near a Fano resonance