Insights into atomic structure of next-generation superconductors

Insights into atomic structure of next-generation superconductors

Neutron diffraction at the Australian Centre for Neutron Scattering has clarified the absence of magnetic order and classified the superconductivity of a new next-generation of superconductors in a paper published in Europhysics Letters.

The iron-based nitride, ThFeAsN, which contains Th2N2 and FeAs2 layers, has been of considerable interest because unconventional superconductivity occurring at a temperature of 30 K. This material was of particular interest as the superconductivity was seen to arise without oxygen doping.

A large group of predominantly Chinese researchers, led by Prof Huiqian Luo from the Beijing National Laboratory for Condensed Matter Physics gathered diffraction measurements on the high intensity diffractometer WOMBAT, assisted by instrument scientists Dr Helen Maynard-Casely and Dr Guochu Deng based at the Australian Centre for Neutron Scattering. This enabled them to determine the crystal structure of the compound over a large temperature range.

In similar types of materials, the onset of a superconducting state is thought to be associated with magnetic ordering within the crystal structure. Earlier measurements had shown no magnetic ordering in the ThFeAsN material, and hence this neutron study was an opportunity to confirm this and search for other structural insights into the material’s properties.

The lack of magnetic order was confirmed because no difference was found between the data sets at 6 K and 40 K. All of the observed reflections could be could be identified as having arisen from the atomic structure from 6K up to 300K – no magnetic reflections were identified.

Diffraction patterns over the temperature range from 300 K to 6 K also indicated there was no structural phase transition from tetragonal to orthorhombic in the crystal lattice.

The investigators reported that the lattice parameters continuously increased with temperature due to thermal expansion and a weak distortion in the tetrahedron possibly took place at 160 K. Details from the structure point to this distortion coming from the FeAs2 layers.

The close relationship between local structure of the FeAs4 tetrahedron and the superconducting temperature, suggested TheFeAsN is in a nearly optimised superconducting state.

This is different to many other discovered superconducting materials, which require tweaks in their chemistry to produce the highest critical temperature.

The authors also surmised that the close distance of Fe-As would favour electron hopping, reducing electron correlations and orbital order, thereby providing a reasonable explanation for the absence of magnetic order, structural transition and resistivity anomaly.

Carrier density measurements indicated that ThFeAsN could already be doped by electrons, which are probably introduced by the N deficiency or O occupancy or the reduced valence of nitrogen. The self-doping effect could be responsible for the superconductivity and suppression of magnetic order.

 

[“Source-phys”]

Google’s New Alphabet structure Sees share costs rising

Alphabet – the brand new maintaining corporation that isolates the middle search and advertisingcommercial enterprise from riskier bets – popular clever domestic accent maker Nest Labs is probablythe most effective unit that will provide traders the returns they crave each time soon.
with the aid of isolating moonshots from moneymakers, Google founders Larry web page and Sergey Brinare now free to pursue more quixotic business thoughts which include glucose-tracking contact lenses,internetrelated, excessive-altitude balloons or even immortality.

buyers cheered the corporate restructuring announced on Monday for giving more visibility into Google’simperative enterprise and regarded much less nerve-racking about zany ventures which could pose as distractions.

but of all the companies in Alphabet – the new conserving company that isolates the core seek andadvertising and marketing enterprise from riskier bets – popular clever domestic accent maker Nest Labs is possibly the only unit with the intention to deliver traders the returns they crave every time soon, analysts instructed Reuters.

They added that Google’s self-driving cars and fitness ventures, such as storing statistics on human DNAwithin the cloud, are doubtlessly worthwhile, but now not for at least several years.

in the near term, buyers are going to awareness on the middle enterprise and give them a few leeway,”said Macquarie studies analyst Ben Schachter.

The company‘s shares rose four in line with cent on Tuesday in the wake of the statement and climbed astons as 7 in step with cent the previous day in after-hours buying and selling.

under the structureseek, marketing, maps, YouTube and Android will continue to be a part of Googlebeneath the management of latest leader government Officer Sundar Pichai, currently the employer‘s product chief. search remains the agency‘s financial engine, riding extra than 90 percent of sales,consistent with analysts.

Nest, anti-growing old employer Calico, clever cities enterprise Sidewalk, secretive lab Google X, as well as Google Capital and Google Ventures – making an investment devices – will all be run separately with their own leaders, Google said. thru those ventures, Google has attempted to perform the entirety fromenhancing public transportation to prolonging the human lifespan.

web page and Brin can be Alphabet’s CEO and president, respectively.

The employer plans to combine the economic results of all ventures outdoor the middle Googlecommercial enterprise, however buyers hope that other corporationsresults could be broken out as they mature.

The high candidate for such scrutiny is Nest, the maker of smart thermostats, smoke detectors and othersafety structures that Google bought closing yr for $three.2 billion.

although Google has not targeted the employer‘s financial overall performance, buyers have motive to be constructive, stated analyst Avi Greengart of present day evaluation.

there is a incredible quantity of layout and engineering,” that go into its products, he said. “they areselling (them) at a earnings.”

Nest might also benefit from greater independence, said analyst Jan Dawson of Jackdaw studies. the purchase sparked worries among customers that Google could suck up data from Nest’s domesticaccessories or positioned advertising on the devices.

Now the relationship is “at arm’s duration again,” said Dawson.

Analysts are constructive that a number of the alternative studies tasks turns into profitablebusinesses. Google has already all started testing its self-using motors close to its Mountain View, California headquarters as it figures out how to crack a doubtlessly big marketplace, while traditionalautomobile makers additionally pursue the generation.

It has also recruited pinnacle researchers for its fitness ventures and will have the flexibility to spend years getting to know and testing merchandise.

however the fledgling ventures may also be looked at extra closely. while traders see simply how tonscash the initiatives are haemorrhaging, they may name for greater discipline, perhaps hamperingdevelopment, stated analyst Patrick Moorhead of Moor Insights & strategy.

“Heck, Google itself misplaced cash for years earlier than it went public,” he stated.

whether ventures thrive or flop, Dawson said, the new shape leaves Google poised for either path ofmovement.

“If one of the new companies starts doing without a doubt properly, they could spin it off greaterwithout difficulty,” he said. “if they do not want to do something any more, it makes it simpler to sell it off.”
© Thomson Reuters 2015