Nav: Home

Special topic: New unconventional superconductors and Weyl semimetal

March 25, 2016

Unconventional superconductivity and topological quantum phenomena are two frontier research directions of condensed matter physics. A special topic published in 2016(5) issue of Science China Physics, Mechanics & Astronomy collected several works covering important progress in these two directions. Superconductivity was discovered in Hg in 1911 by the group of Kamerling Onnes in Leiden (Holland). The mystery of superconductivity was, however, not uncovered until 1957 when Bardeen-Cooper-Schrieffer (BCS) proposed the electron-phonon coupling picture. In the BCS picture, two electrons near the Fermi surface with opposite momenta and spins will form a bound state by exchanging phonons. Such charge carriers are called as Cooper pairs. Cooper pairs will condense into a low-energy state, which exhibits macroscopic phase coherence with, of course, the presence of a superfluid. The validity of this theory is, however, quite limited, and it cannot explain superconductivity in many unconventional superconductors, such as cuprates, iron pnictides, and iron selenides.

On the topic of unconventional superconductivity, four works were presented in this special collection. The first work [1] concerns the effect of impurity scattering on superconductivity in K2Cr3As3, an unconventional superconductor discovered in 2015 by the same group here. This superconductor may contain a one-dimensional superfluid channel and possess the rarely reported triplet superconductivity. The report by the group of Prof. Guang-Han Cao from Zhejiang University deals with the effect of impurity resulting from dopants, which may reveal the fundamental feature of the pairing manner. They found the suppression of superconductivity by non-magnetic impurities, which is consistent with a possible novel pairing gap with, for example, gap nodes. The second work [2] by the group of Prof. JianLin Luo of the Institute of Physics, Chinese Academy of Sciences, involves NMR studies of the recently discovered superconductor MnP under pressure. Superconductivity was discovered by the same group in MnP under pressure. The chiral magnetic state seems to be essential to the superconductivity in that system. Here, the authors put new efforts into this issue. The third work [3] is by Prof. Hai-Hu Wen's group from Nanjing University. Since the discovery of the superconductor (Li1?xFex)OHFeSe, the question remains as to whether the superconductivity is robust and has a full volume. Clearly, the authors report robust superconductivity and anisotropy of the newly discovered superconductor (Li1?xFex)OHFeSe. Using well-documented data and analysis, they concluded a full volume of superconductivity in this new superconductor. The fourth work [4] is by the group of Prof. ShiYan Li from Fudan University. They use elegant thermal transport measurements at very low temperatures to detect the superconducting gap structure of the new superconductor Ca10(Pt4??As8)((Fe1?xPtx)2As2)5 (Tc=22 K). They find strong evidence of a fully gapped feature, the gap structure of which is common with many other iron-based superconductors.

Finally, the special topic collected one paper [5] by the group of Prof. MingHu Fang from Zhejiang University on the transport properties of the theoretically predicted Weyl semimetal TaP. Weyl semimetal is a very hot topic involving interesting physics. The detailed and careful transport measurements reveal not only the features of a semimetal but also some evidence of the chiral feature of the electrons, such as the huge positive and negative magnetoresistance. This discovery will trigger further studies on the Weyl semimetal state.
See the articles:

1. Effect of impurity scattering on superconductivity in K2Cr3As3
Yi Liu, Jin-Ke Bao, Hao-Kun Zuo, Abduweli Ablimit, Zhang-Tu Tang, Chun-Mu Feng, Zeng-Wei Zhu, and Guang-Han Cao
Sci. China-Phys. Mech. Astron. 59, 657402 (2016)

2. 31P NMR study of magnetic phase transitions of MnP single crystal under 2 GPa pressure
GuoZhi Fan, Bo Zhao, Wei Wu, Ping Zheng, and JianLin Luo
Sci. China-Phys. Mech. Astron. 59, 657403 (2016)

3. Robust superconductivity and transport properties in (Li1-xFex)OHFeSe single crystals
Hai Lin, Jie Xing, XiYu Zhu, Huan Yang, and Hai-Hu Wen
Sci. China-Phys. Mech. Astron. 59, 657404 (2016)

4. Nodeless superconducting gaps in Ca10(Pt4-δAs8)((Fe1-xPtx)2As2)5 probed by quasiparticle heat transport
Xun Qiu, LanPo He, XiaoChen Hong, Zhen Zhang, Jian Pan, XiaoPing Shen, DongLai Feng, and ShiYan Li
Sci. China-Phys. Mech. Astron. 59, 657405 (2016)

5. Large unsaturated positive and negative magnetoresistance in Weyl semimetal TaP
JianHua Du, HangDong Wang, Qing Chen, QianHui Mao, Rajwali Khan, BinJie Xu, YuXing Zhou, YanNan Zhang, JinHu Yang, Bin Chen, ChunMu Feng, and MingHu Fang
Sci. China-Phys. Mech. Astron. 59, 657406 (2016)

Science China Press

Science China Press

Related Superconductivity Articles:

How a magnet could help boost understanding of superconductivity
Physicists have unraveled a mystery behind the strange behavior of electrons in a ferromagnet, a finding that could eventually help develop high temperature superconductivity.
New study explains why superconductivity takes place in graphene
Theoretical physicists take important step in development of high temperature superconductors.
Better studying superconductivity in single-layer graphene
A new study published in EPJ B demonstrates that an existing technique is better suited for probing superconductivity in pure, single-layer graphene than previously thought.
Stressing metallic material controls superconductivity
No strain, no gain -- that's the credo for Cornell researchers who have helped find a way to control superconductivity in a metallic material by stressing and deforming it.
First report of superconductivity in a nickel oxide material
Scientists at SLAC and Stanford have made the first nickel oxide material that shows clear signs of superconductivity - the ability to transmit electrical current with no loss.
A hallmark of superconductivity, beyond superconductivity itself
Physicists have found 'electron pairing,' a hallmark feature of superconductivity, at temperatures and energies well above the critical threshold where superconductivity occurs.
Manipulating superconductivity using a 'mechanic' and an 'electrician'
Strongly correlated materials can change their resistivity from infinity to zero with minute changes in conditions.
Triplet superconductivity demonstrated under high pressure
Researchers in France and Japan have demonstrated a theoretical type of unconventional superconductivity in a uranium-based material, according to a study published in the journal Physical Review Letters.
The mechanism of high-temperature superconductivity is found
Russian physicist Viktor Lakhno from Keldysh Institute of Applied Mathematics, RAS considers symmetrical bipolarons as a basis of high-temperature superconductivity.
Superconductivity is heating up
Theory suggests that metallic hydrogen should be a superconductor at room temperature; however, this material has yet to be produced in the lab.
More Superconductivity News and Superconductivity Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Reinvention
Change is hard, but it's also an opportunity to discover and reimagine what you thought you knew. From our economy, to music, to even ourselves–this hour TED speakers explore the power of reinvention. Guests include OK Go lead singer Damian Kulash Jr., former college gymnastics coach Valorie Kondos Field, Stockton Mayor Michael Tubbs, and entrepreneur Nick Hanauer.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Dispatch 6: Strange Times
Covid has disrupted the most basic routines of our days and nights. But in the middle of a conversation about how to fight the virus, we find a place impervious to the stalled plans and frenetic demands of the outside world. It's a very different kind of front line, where urgent work means moving slow, and time is marked out in tiny pre-planned steps. Then, on a walk through the woods, we consider how the tempo of our lives affects our minds and discover how the beats of biology shape our bodies. This episode was produced with help from Molly Webster and Tracie Hunte. Support Radiolab today at