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Metamaterials Can Reduce Electrons’ Effective Mass to Nearly Zero
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The field of metamaterials involves augmenting materials with specially designed patterns, enabling those materials to manipulate electromagnetic waves and fields in previously impossible ways. Now, researchers from the University of Pennsylvania have come up with a theory for moving this phenomenon onto the quantum scale, laying out blueprints for materials where electrons have nearly zero effective mass.
Their idea was born out of the similarities and analogies between the mathematics that govern electromagnetic waves — Maxwell’s Equations — and those that govern the quantum mechanics of electrons — Schrödinger’s Equations.
On the electromagnetic side, inspiration came from work the two researchers had done on metamaterials that manipulate permittivity, a trait of materials related to their reaction to electric fields. They theorized that, by alternating between thin layers of materials with positive and negative permittivity, they could construct a bulk metamaterial with an effective permittivity at or near zero. Critically, this property is only achieved when an electromagnetic wave passes through the layers head on, against the grain of the stack. This directional dependence, known as anisotropy, has practical applications.
The researchers saw parallels between this phenomenon and the electron transport behavior demonstrated in Leo Esaki’s Nobel Prize-winning work on superlattices in the 1970s: semiconductors constructed out of alternating layers of materials, much like the permittivity-altering metamaterial.
Physical Review B – Transformation electronics: Tailoring the effective mass of electrons
See more and subscribe to NextBigFuture at 2012-12-19 02:22:30 Source: http://nextbigfuture.com/2012/12/metamaterials-can-reduce-electrons.html
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