Apr 11, 2013 |
First experimental observation of the quantum anomalous Hall effect could revolutionize electronics
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(Nanowerk News) Chinese scientists have made the very first experimental observation of a phenomenon known as the quantum anomalous Hall (QAH) effect ("Experimental observation of the quantum anomalous Hall effect in a magnetic topological insulator"), a discovery that will help accelerate the IT revolution and in developing low-power-consumption electronics.
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Yang Zhenning, winner of a Nobel Prize in Physics, said at a press conference on Wednesday that the research was ground-breaking in the field, rating it as worthy of a Nobel Prize.
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QAH effect is one of the most important physical effects that had remained unobserved worldwide, according to academic Xue Qikun, who has led a team working on the subject since 2008.
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Schematic illustration of the quantum anomalous Hall effect: when the chemical potential is tuned into the energy gap at the Dirac point of a ferromagnetic topological insulator, the zero magnetic field anomalous Hall conductance σxy(0) reaches the quantized value e2/h and forms a plateau, whereas the longitudinal conductance σxx(0) drops to 0.
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The discovery, if it is harnessed in the future, will help reduce unnecessary energy consumption stemming from irregular electron collisions, according to Xue.
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"The technology may even bring about a supercomputer in the shape of an iPad," predicted Xue.
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The QAH effect was predicted to occur in magnetic topological insulators by American scientist Edwin Hall more than 130 years ago. It is a kind of quantum Hall effect realized at zero magnetic field.
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The quantum Hall effect describes how a voltage appears at both semiconductor edges when the electrons on a current-carrying semiconductor experience a force while being kept in a magnetic field, Xue explained.
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Experimental results showing the quantum anomalous Hall effect: the different curves represent the field dependence of the Hall resistance measured at varied gate voltages. Within a certain range of gate voltages, the zero magnetic field anomalous Hall resistance reaches the quantized value h/e2.
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The academic said that although leapfrog development has been made in semiconductor technology, the unsettled problem of thermal dissipation caused by irregular movements of electrons has created a bottleneck for the IT industry's further development.
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The research, launched by a team of scientists from Tsinghua University and the Institution of Physics under the Chinese Academy of Science, was conducted on more than 1,000 samples at zero magnetic fields.
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However, there remains a long way ahead for the observation to be taken into practical application due to limited research resources at present, Xue added.
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