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But the surprising result for the researchers was that at an intermediate thickness, ranging from two to six atomic layers, the selectivity of the interface completely changes.
"We see a dramatic and complete reversal in the spin of electrons that pass through the interface," said Roland Kawakami, an assistant professor of physics who led the research team. "This time, spin up electrons pass through while spin down electrons are reflected back to the semiconductor. In other words, the thickness of the MgO interface determines whether spin up or spin down electrons are allowed to pass through it."
According to his research team, such a "spin reversal" can be used to control current flow.
Significance of the discovery:
"Electron spins are oriented at random in an ordinary electric circuit, and, therefore, do not affect current flow," explained Yan Li, the first author of the research paper, who made the discovery. "But if spin is polarized, that is, aligned in one direction, you can manipulate the flow of current and the transport of information a feature that would be of great interest to the semiconductor industry. What is amazing is that only a couple of atomic layers of MgO can completely reverse the spin selection of the interface. This is unexpected because MgO is not a magnetic material."
Li, a graduate student in the Department of Physics and Astronomy working toward her doctorate in physics, said the research team will work next on making electronic devices based on the spin reversal. "This will not only test its feasibility for applications, but also help determine the cause of the spin reversal, which is still unclear," she said.
Kawakami's lab is one of very few labs in the world that perform both the advanced mat
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| Contact: Iqbal Pittalwala iqbal@ucr.edu 951-827-6050 University of California - Riverside Source:Eurekalert |