Observation of Griffiths phase at an anti-ferromagnetic quantum critical point in Ce(Cu1-xCox)2Ge2
Abstract
A comprehensive study has been carried out on polycrystalline samples of Ce(Cu1-xCox)2Ge2 by means of electrical resistivity, magnetic susceptibility, specific heat and thermo electric power measurements. The long-range antiferromagnetic order, at TN = 4.1 K in CeCu2Ge2, is suppressed by non-iso-electronic cobalt (Co) doping at a critical value of the concentration xc = 0.6, accompanied by non-Fermi-liquid behavior. A power-law dependence of heat capacity and susceptibility i.e. C(T)/T and ξ(T) T -1+λ down to 0.4 K are observed around xc = 0.6 which is compatible with the quantum Griffiths phase scenario and attributed to an antiferromagnetic quantum critical point. Our results on Ce(Cu1-xCox)2Ge2 manifest a complex magnetic phase diagram, where we have observed a continuous decrease of TN with large negative slope down to TN = 0.83 K at x = 0.1, and then a comparatively small negative slope takes over. We conclude that the rapid decrease of TN upon Co-doping is mainly due to carrier concentration change and associated change of TK and TRKKY . We have not seen any superconducting phase in the quantum critical regime down to 0.4 K.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- 2019
- Bibcode:
- 2019APS..MARR06005T