1. Experiment Method: 𝝁𝑺𝑹
Quantum criticality in single crystalline YFe2Al10 determined by Muon Spin Relaxation(𝜇𝑆𝑅)
C. Tan1, K. Huang1, J. Zhang1, Z.F. Ding1, L. S. Wu2, M. C. Aronson2,3, and L. Shu1
1Department of Physics, Fudan University, Shang Hai, China
2Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794,
3Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973
Introduction
𝑳𝑭−𝝁𝑺𝑹
YFe2Al10 belongs to a novel class of caged compounds of the form MT2X10. Previous measurements found no evidence of magnetic order in YFe2Al10, but the scaling of susceptibility, heat capacity and resistivity hints its proximity to a ferromagnetic instability and it is a rare example of quasi-2D metallic system. We find strong signatures of quantum criticality from muon spin relaxation and rotation, a powerful measurement for detecting very small and localized magnetism.
L.S.Wu et.al PNAS(2014)
Left-top panel: Asymmetry as a function of time for YFe2Al10 at K at various applied fields(fitting function shows below).
Left-top panel: time field scaling observed at 0.019K with exponent 0.73
Right figure: relaxation rate as a function of applied field at K(blue) and 0.1K(red) respectively. Fitted to the function 𝝀 = 𝒂 𝑯 𝒃
Experiment Method: 𝝁𝑺𝑹
Left figure is schematic of a zero field(ZF) 𝜇𝑆𝑅 setup. Here one measure the time evolution of muon polarization along its original direction without external magnetic field. ZF 𝜇𝑆𝑅 is a very sensitive method of detecting weak internal magnetism, that arises due to ordered magnetic moments, or random fields that are static or fluctuating with time. When apply an external field parallel to the initial direction of the muon spin polarization, it is longitudinal field(LF) 𝜇𝑆𝑅.
Table above gives fitting result of relaxation rate variation with longitudinal field at different temperature.
𝐴 𝑡 = 𝐴 0 {1− 2 𝜎 2 (2𝜋𝜈) 2 1− 𝑒 − 𝜎𝑡 2 cos 2𝜋𝜈𝑡 𝜎 4 (2𝜋𝜈) 𝑡 𝑒 − 𝜎𝑡 sin 2𝜋𝜈𝜏 𝑑𝜏 } 𝑒 −𝜆𝑡
𝒁𝑭−𝝁𝑺𝑹
𝒁𝑭−𝒃 𝒂𝒙𝒊𝒔
The left graph displays the relaxation rate as function of temperature. While the incident muon along b-axis of single crystalline YFe2Al10.
Single crystalline(c axis)
Polycrystalline
D. T. Adroja et al., Phys. Scr (2013)
The top two figures display the asymmetry variation with time . Interestingly, there is a temperature dependence of the asymmetry spectrum for the single crystal (top-left) which was not found in the polycrystalline material (top-right).
The left graph displays the relaxation rate for single crystalline YFe2Al10. The fitting function(shows below) describe the time evolution of asymmetry at different temperature. Where 𝝈 related to the static nuclear dipole, 𝝀 represent the electronic dynamic spin fluctuation.
Conclusion
YFe2Al10 exhibit a notable temperature dependence of the muon relaxation rate below 1K, indicate the slow down of dynamic spin fluctuation.
The LF spectrum obeys time-field scaling for applied field up to 100Oe(P(t)=P(t/H𝛾)), but failed for 1.19K experiment data due to the system move away from the quantum critical point with increasing temperature.
𝐴 𝑡 = 𝐴 0 { − 𝜎𝑡 2 exp⁡(− 𝜎𝑡 2 )} 𝑒 −𝜆𝑡
Contact
Acknowledgment
Reference
This work was supported by the National Natural Science Foundation of China ( ), and the National Natural Science Foundation of China ( )
L.S. Wu et.al PNAS(2013), D.T. Adroja et.al PRB(2008), J. Spehling et.al PRB(2012), S. Lausberg et.al PRB(2012)
C. Tan
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