baseball pitchers often turn the ball to make a curve to the left or electron spin derecha.Los moved through a semiconductor may also follow curved paths because of the way they bounce off the atoms and other particles fixed. However, in an upcoming issue of Physical Review Letters experimental team shows that this effect of spin Hall "should persist even when the electrons move smoothly and without dispersion, as would be a future generation of devices very small. The results suggest that the effect will be a powerful tool to control money flows both as load devices in future "spintronics."
The researchers believe that the effect of "Hall spin "is linked to the call interaction spin-orbit between spin of an electron and its physical movement. Previous experiments have shown the effect when the electrons move through a material in the form of a pinball chaos, shaken by frequent colisiones.Cuando the electrons bounce off the obstacles, his spin gives an extra pull to the right or left - depending on their direction of rotation, in the same measure of money they get when billiard balls collide with obstacles.
eight years ago, however, theorists suggested that the subtle details of interaction spin-orbit could cause a similar drift sideways, even in materials through which electrons glide smoothly without dispersión.Para find this "intrinsic" spin Hall effect, Hui Zhao and his colleagues at the University of Kansas in Lawrence tried to take a snapshot of the flow of electrons in such a short time could not be dispersed.
The team experienced in the flow of electrons that are injected into a sample of gallium arsenide . They first used lasers to create two equal currents of electrons traveling in opposite directions, having a current clockwise spin (spin down) the other with a counterclockwise spin (spin up). Together, these two trends created a pure spin current - a net flow of spin, or angular momentum , but net flow of electric charge.
electron spin (upwards) Eastbound cancel the load current of electrons (spin down) traveling west (dotted line), leaving only a stream of spin (blue arrow) . Both strands bend towards the north due to the spin Hall effect and generate an electrical current to the lados.Nuevos experiments show that this effect occurs "intrinsically" in the absence of dispersión.Crédito.H. Zhao / Univ. of Kansas.
The pure spin current should create a small amount of current in the direction toward the sides (the effect sometimes called "inverse" spin Hall) as the two current components are curved in the same direction. For example, if the currents to the east and west, both curves to the north a bit, it generates a small movement of electrons toward the north. To find this effect, the team used a second laser to display the load change to the side. They found a sideways movement of about 0.1 nm that became evident in a time of just 0.1 picoseconds.
To test whether the effect Hall of spin was caused by electron scattering, the researchers measured the speed with which the initial spin current disappeared due to the scattering of electrons and found a time of about 0.45 ps. Since the current sideways appeared long before many dispersal events could have occurred, concluded that the current could not have been caused by dispersion.
"I think this is the first direct measurement of the spin Hall opposite effect on times shorter than the dispersion time," says Allan MacDonald, University of Texas at Austin. He says the biggest impact of this work at last instance, may be in understanding the behavior of the electron over long times larger devices.
Zhao said that an electron in a semiconductor moves between 10 and 100 nm between two subsequent collisions. Integrated circuit devices today have a size of about 50 nanometers to 20 nanometers coming soon, so that the electrons experience very few collisions in next-generation devices. "The spin Hall effect based on the dispersion is not going to work," says Zhao. "But the direct impact may provide a technique for generating and detecting spin currents, even on more devices small. "
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source of information:
http://focus.aps.org/story/v27/st8 # author
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