Three physicists Andre Petukhov of the South Dakota School of Mines and Technology, Rafa Oszwa Dowski and Igor Žutiæ, University at Buffalo have stated in a paper, Physical Review Letters, that magnetic properties may not remain the same at the nanoscale.
A quantum dot’s two mobile electrons will actually influence the manganese spins differently.
They discovered that quantum dot, a form of nanoparticles, can be produced with magnetic properties under certain conditions.
Electron spin, either upward spin or downward spin, determines the magnetic property of a substance. If most of the electrons have same spin, then the material is magnetic. Mobile electrons are capable of using their own spin to align the spins of adjacent atoms, which make them magnetic messengers. However, when two mobile electrons with opposite spins stay close, the material loses it magnetic power as the powers get cancelled. The team from UB-South Dakota has observed that a strange form of magnetism is prevalent in quantum dots whose mobile electrons have opposite spins.
The researchers experimented their finding using quantum dot that comprise two free-floating mobile electrons spinning at opposing directions, together with manganese atoms embedded at particular positions within the quantum dot; and identified a strange form of magnetism in quantum dot. In contrast to the usual prediction, each mobile electron exerted an equal pressure over manganese atoms spin which could not defeat each other. Yet, Petukhov and Oszwa Dowski, Žutiæ found that two mobile electrons can affect the manganese atoms spin because when one mobile electron occupies middle space of quantum dot, the other stays at the edges. Hence, two mobile electrons send two different messages to manganese atoms to align their spins. In this war, electrons that interact more forcefully will succeed in aligning more spins. This makes quantum dot magnetic in nature. When there is a single moving electron in the quantum dot, the mobile electron will send a message and align the spins of adjacent manganese atoms.
Žutiæ stated that this discovery was applied in Spintronic gadgets which stored and processed data by exploiting electrons in up and down spins.
Source: www.buffalo.edu