title: Effective mass enhancement and spin-glass behaviour in CeCu4Mn(y)Al(1-y) compounds.
abstract: We report on the magnetic ac/dc susceptibility and specific heat measurements for the CeCu(4)Mn(y)Al(1-y) series of compounds with 0 ≤ y ≤ 1. All compounds investigated crystallize in the hexagonal CaCu(5)-type structure with the space group P6/mmm. The results reveal that the frustration of the interactions dominates and leads to a spin-glass (SG) behaviour with a linear change of the freezing temperature T(f) as a function of y. The SG state has been confirmed by the frequency dependence of the ac magnetic susceptibility, the relaxation of the remanent magnetization and the split of the field-cooled-zero-field-cooled dc magnetic susceptibility. The electronic specific heat coefficient γ is enhanced for all y and increases with the Al content. Below a threshold at y ≈ 0.3, γ is large even if determined for temperatures above T(f); moreover the paramagnetic Curie-Weiss temperature θ(p) changes sign to negative. These observations indicate the possible presence of the heavy fermion (HF) state, at least below y ≈ 0.3, and the possible coexistence of the SG and HF states down to y = 0, i.e. for the CeCu(4)Al compound. A tentative magnetic phase diagram for CeCu(4)Mn(y)Al(1-y) has been constructed.
authors.affiliation: Institute of Molecular Physics, Polish Academy of Science, M Smoluchowskiego 17, PL-60-179 Poznań, Poland. karol.synoradzki@ifmpan.poznan.pl
authors.forename: K
authors.initials: K
authors.lastname: Synoradzki
authors.forename: T
authors.initials: T
authors.lastname: Toliński
mesh_terms: D000535:Aluminum / Q000737:chemistry*; D002586:Cesium / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D005898:Glass / Q000737:chemistry*; D006358:Hot Temperature; D008280:Magnetics; D008345:Manganese / Q000737:chemistry*; D008958:Models, Molecular; D013113:Spin Labels
chemical_list: D013113:Spin Labels; D002586:Cesium; D008345:Manganese; D003300:Copper; D000535:Aluminum