Observation of field induced anomalous quantum criticality in Ce0.6Y0.4NiGe2 compound

Abstract

We report the results of our investigation of magnetization and heat capacity on a series of compounds Ce 1-x Y x NiGe 2 (x = 0.1, 0.2 and 0.4) under the influence of external magnetic field.Our studies of the thermodynamic quantity -dM/dT on these compounds indicate that magnetic frustration persists in Ce 0.9 Y 0.1 NiGe 2 , as also reported for the parent compound CeNiGe 2 . The weak signature of this frustration is also noted in Ce 0.8 Y 0.2 NiGe 2 , whereas, it is suppressed in Ce 0.6 Y 0.4 NiGe 2 . Heat capacity studies on Ce 0.9 Y 0.1 NiGe 2 and Ce 0.8 Y 0.2 NiGe 2 indicate the presence of a new magnetic anomaly at high field which indicates that quantum criticality is absent in these compounds. However, for Ce 0.6 Y 0.4 NiGe 2 such an anomaly is not noted. For this later compound, the magnetic field (H) and temperature (T) dependence of heat capacity and magnetization obey H/T scaling above critical fields. However, the obtained scaling critical parameter (δ) is 1.6, which is away from mean field value of 3. This deviation suggests the presence of unusual fluctuations and anomalous quantum criticality in these compounds. This unusual fluctuation may arise from disorderness induced by Y-substitution.

Entropic topography associated with field-induced quantum criticality in a magnetic insulator DyVO4

“…Field induced quantum criticality has been reported in many systems, such as in CoNb 2 O 6 8 , CeAuSb 2 13 , CeCoIn 5 14 , YbRh 2 Si 2 15 , 16 , Sr 3 Ru 2 O 7 17 – 19 , CePtIn 4 20 and many more. Field tuned anomalous quantum criticality has also been observed in Y-substituted CeNiGe 2 21 . Quantum criticality has also been studied in some transition metal oxides.…”