Ultra-low temperature ac susceptibility of the heavy-fermion superconductor YbRh2Si2

International Conference on Strongly Correlated Electron Systems 2016

Steinke, L.^1 ; Schuberth, E.^1,2 ; Lausberg, S.^1 ; Tippmann, M.^2 ; Steppke, A.^1 ; Krellner, C.^1,3 ; Geibel, C.^1 ; Steglich, F.^1,4,5 ; Brando, M.^1

Max Planck Institute for Chemical Physics of Solids, Dresden

01187, Germany^1

Walther Meissner Institut fur Tieftemperaturforschung der Bayerischen Akademie der Wissenschaften, Garching

85748, Germany^2

Physics Institute, University of Frankfurt, Frankfurt

60438, Germany^3

Center for Correlated Matter, Zhejiang University, Hangzhou, Zhejiang

310058, China^4

Institute of Physics, Chinese Academy of Sciences, Beijing

100190, China^5

关键词: Ac susceptibility;    Antiferromagnetics;    Field dependence;    Heavy fermion systems;    Paramagnetic state;    Second-order phase transition;    Ultra low temperatures;    Very low temperatures;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/807/5/052007/pdf
DOI  :  10.1088/1742-6596/807/5/052007

来源: IOP

【 摘 要 】

Recently, we reported on the discovery of superconductivity in YbRh2Si2at the very low temperature Tc= 2 mK. We present here complementary measurements of the temperature and field dependence of the ac susceptibility χac(T) of this heavy-fermion system for temperatures down to 1 mK and magnetic fields in the basal plane up to 75 mT. The in-phase response shows a steep drop at Tc, but it does not become negative, possibly because of the presence of the earth field that was not compensated. The out-of-phase response shows an increase right below Tcindicating that the transition is first order. We also observe two kinks in the field dependence of χac(B) at B1≈ 50 mT and B2≈ 60 mT, which imply a more complex T - B phase diagram for YbRh2Si2with B ⊥ c. These features possibly indicate two second-order phase transitions or domain reorientation at B1and a phase transition from the antiferromagnetic to the paramagnetic state at B2.