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英国皇家化学协会<chemistry world>关于发现外尔费米子的报导

已有 3862 次阅读 2015-7-21 16:46 |系统分类:观点评述| fermion, Weyl, 外尔半金属, 外尔费米子, Semimetal

2015716日,英国皇家化学协会的《Chemistry World》发布新闻,报导了实验发现外尔费米子(Weyl Fermion)的科学事件。

该科学媒体完全独立于中科院物理所,普林斯顿以及麻省理工,并做了细致的信息查证工作,全面、公正的反映了这个科学事件中各方做出的实际贡献。我把原文和部分译文放在这里,供大家阅读。

原文链接:

http://www.rsc.org/chemistryworld/2015/07/elusive-weyl-fermion-found-long-last 


Elusive fermion found at long last

 

Two international teams claim to have found the basicbuilding block of the electron, the Weyl fermion, which was first theorised 86years ago.1,2两个国际团队声称发现了电子的基本构成模块——86年前理论提出的外尔(Weyl)费米子。这里的参考文献2就是中科院物理所团队的实验工作。]The discovery of this new sub-atomic particlewas not made in a particle collider, however, but inside a synthetic crystal.The fermion, which is massless, could potentially give rise to super-fastelectronics and photonics, the discoverers claim.

 

Weyl fermionsare fundamental particles that were first predicted by Hermann Weyl back in1929, but they have never been observed experimentally. Theoretically, they areobservable in materials called Weyl semimetals, which fulfil special conductionand symmetry criteria. Scientists haven’t been able to ever find or make a Weylsemimetal though, because achieving the right electronic structure usuallyrequires fine-tuning the material’s chemical composition. But earlier this yeartwo independent research teams predicted that tantalum arsenide would displayWeyl semimetal character without needing any problematic fine-tuning.3,4但是今年初,两个独立研究团队预言砷化钽(TaAs)将会表现出外尔半金属的特性而无需任何麻烦的细致调控。 这里参考文献3是中科院物理所团队的理论预言工作。


Both groupshave now followed up on their prediction by making a tantalum arsenide crystaland using it to observe the Weyl fermion. ‘This is the first time ever, in allof physics, that Weyl fermions have been observed,’ says Zihad Hasanfrom the University of Princeton, US, who is leading one of the groups. Thecrystal was subjected to angle-resolved photoemission spectroscopy (ARPES), adirect experimental technique used for studying electronic structure. ‘Insidethe crystal, electrons behave like they’re massless and chiral,’ Hasanexplains, ‘and this is direct evidence of Weyl fermions.’

The fermion maybe used to create massless electrons with very high mobility and nobackscattering at all. Backscattering from normal electrons greatly reduceselectronic efficiency, so the hope is that Weyl electrons can play an importantrole in the development of new, faster electronics. ‘Tantalum arsenide alreadyhas higher mobility than graphene,’ Hasan says. ‘You can create a new kind ofelectronics, so I’m coining this term: weyltronics.’

 

‘A new type ofelectronic system is always potentially interesting,’ says AshvinVishwanath from the University of California, Berkeley, US, whowasn’t involved with any of the studies, ‘although it is early days to know howthese will be applied. It is worth noting that Weyl materials are direct 3Delectronic analogues of graphene, which is being seriously studied forpotential applications.’

 

A third group has just announced that it has observed the fermion in a photonic 3Dgyroid crystal, and they also suggest that it could inspire anew generation of photonics.5[这里参考文献5是麻省理工小组在光子晶体中发现Weyl费米子]

 

REFERENCES

1 Z Hasan et al, 2015, Science,DOI: 10.1126/science.aaa9297

2 H Weng et al,2015, arXiv: 1502.04684

3 H Weng et al,2015, Phys. Rev. X, DOI: 10.1103/physrevx.5.011029

4 Z Hasan et al, 2015, Nat.Commun., DOI:10.1038/ncomms8373

5 L Lu et al, 2015, Science,DOI: 10.1126/science.aaa9273




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