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学术报告    Superconducting ground state of new superconductors A2Cr3As3(A=K and Cs) and ThFeAsN investigated using μSR measurements


【报告题目】 Superconducting ground state of new superconductors A2Cr3As3(A=K and Cs) and ThFeAsN investigated using μSR measurements
【报 告 人】 Dr. Devashibhai Adroja
              Senior Scientist, ISIS Facility, Rutherford Appleton Laboratory, UK
【时 间】 2017-06-12     星期一10:00
【地 点】 理工楼801

【报告摘要】

The superconducting state of the newly discovered superconductors A2Cr3As3 (A=K and Cs, TC=6 K and 2.1 K, respectively) and ThFeAsN (Tc=30K) have been investigated using magnetization and muon-spin relaxation or rotation (μSR)measurements [1, 3].Our analysis of the transverse field (TF) µSR results of A2Cr3As3 (A=K and Cs) shows that the temperature dependence of the superfluid density, obtained from TF-μSR measurements, fits better toa nodal gap structure than an isotropic s-wave model. Therefore our μSR analysis is more consistent with having line nodes than being fully gapped in A2Cr3As3 (A=K and Cs).This result is in agreement with the results of the penetration depth measured using a tunnel diode oscillator technique on A=K [4]. Further our zero-field (ZF) μSR measurements do reveal very weak evidence of the spontaneous appearance of an internal magnetic field below the transition temperature. This observation suggests that the electrons are paired via unconventional channels such as spin fluctuations, as proposed on the basis of theoretical models. On the other hand the analysis of TF-µSR results of ThFeAsN shows a possibility of an isotropic s-wave gap. We will present the results of the magnetic penetration depth λL, superconducting carrier density ns, and effective-mass enhancement mestimated from the TF-µSR measurements of these three compounds.

*devashibhai.adroja@stfc.ac.uk

Thiswork is supported by STFC, The Royal Society of London, Shanghai Pujiang

Scholar Program (Grant No.13PJ1401100), NSFC,MOST and CAS.

References:

[1]D.T. Adroja et al , Phys. Rev B 92, 134505 (2015)

[2]D.T. Adroja et al, J. Phys. Soci. Japn, 86, 044710 (2017)

[3] D.T. Adroja et al, Phys. Rev. B  to be submitted(2017).

[4] G.M. Pang et al, Phys. Rev. B 91, 220502(R) (2015)


【报告人简介】

Dr Adroja is a senior scientist at the ISIS facility and is responsible for the MERLIN spectrometer and he is also a visiting professor at Johannesburg University, South Africa. His research programme is focused on strongly correlated electron systems with more than 24 years of experience in neutron scattering and muon spin rotation technique. Dr Adroja obtained his Ph.D. from IIT Bombay (in 1991), India, and then worked as a research fellow at Southampton, Hiroshima (JSPS fellowship 1997), St Andrews universities before joining ISIS in 1999. Since 2001, he work at ISIS as an instrument scientist in Excitations group,  then from 2007 to present, he become a Senior Scientist at ISIS. He was the pioneer in discovering the Kondo insulator CeRhS, and the related materials Ce(NiCo)Sn and CePdSb. Recently he has made significant contributions to the field of spin and charge gap formation in strongly correlated electron systems and published two review papers on this topic. He has published over 290 papers in peer-review journals.


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