Non-magnetic Anomaly at 1K Arising in Ferromagnetic Ce2.15(Pd1-xAgx)1.95In0.9

Abstract

Magnetic and thermal properties of Ferromagnetic (FM) Ce2.15(Pd1-xAgx)1.95In0.9 alloys were studied in order to determine the Quantum Critical Point (QCP) at TC → 0. The in- crease of band electrons produced by Pd/Ag substitution depresses TC (x) from 4.1K down to TC (x = 0.5)=1.1K, with a QCP extrapolated to xQCP ≥ 0.5. Magnetic susceptibility from T > 30K indicates an effective moment slightly decreasing from μeff =2.56μB to 2.4μB at x=0.5. These values and the paramagnetic temperature θP ≈ -10K exclude significant Kondo screening effects. The TC (x) reduction is accompanied by a weakening of the FM magnetization and the emergence of a specific heat Cm(T) anomaly at T∗ ≈ 1K, without signs of magnetism detected from AC-susceptibility. The magnetic entropy collected around 4K (i.e. the TC of the x = 0 sample) practically does not change with Ag concentration: Sm(4K) ≈ 0.8 Rln2, suggesting a progressive transfer of FM degrees of freedom to the non-magnetic (NM) compo- nent. No antecedent was found concerning any NM anomaly emerging from a FM system at such temperature. The origin of this anomaly is attributed to an entropy bottleneck originated in the nearly divergent power law dependence for T > T∗

Competition between ferromagnetism and frustrated antiferromagnetism in quasi 2D Ce2.15(Pd1−xAgx)1.95In0.9alloys

“…In FM alloys, the electronic concentration is increased by an excess of Ce in the TM-X layer mainly substituting In atoms but also Pd ones. There is, however, an exception to this dependence observed in Ce 2.15 Pd 1.95 In 0.9 alloys doped with Ag because their T x C ( ) decrease despite of the electron-like character of the dopant [13]. This apparently contradictory behavior of Ag doped alloys in comparison to isotypic alloys with other TM elements was tentatively attributed to an arising magnetic frustration.…”

“…However, in the system at hand the frustration character increases with Ag content. In this work we present a more extended investigation of this system by doubling the number of alloys in comparison to a preliminary study published elsewhere [13], after an accurate characterization of its structural properties and samples quality. New and more detailed results allows to get insight on the magnetization properties and entropy evolution with Ag content.…”