Unusual temperature dependence in the low-temperature specific heat ofU3Ni5Al19

Abstract

Specific heat has been measured down to 0.053 K on a single crystal of the heavy-fermion antiferromagnet U 3 Ni 5 Al 19 that orders at T N = 23 K. As has been previously reported, these data can be fitted between 0.4 and 4 K by the spin-fluctuation model of Moriya and Takimoto, which describes the contribution of weakly interacting critical spin fluctuations to the specific heat, C, where, as T → 0, C / T = ␥ 0 − a ͱ T. However, below 0.35 K a noticeable divergence in C / T ϳ log T dependence, consistent with the existence of strongly interacting fluctuations, is observed. This increase in the divergence of C / T at the lowest temperatures-which is contrary to the self-consistent renormalization theory of Moriya and Takimoto, which predicts ͱT dependence for C / T as T → 0 and log T dependence at higher temperatures-has been measured as a function of magnetic field to further understand its origin. The field data in the low-temperature regime, where C / T ϳ log T exhibit scaling with ⌬B / T 1.9 , further evidence that there exist strongly interacting fluctuations below 0.35 K in U 3 Ni 5 Al 19 .

Physical properties of GdFe2(AlxZnNi1, Jia2, Samolyuk3 et al. 2011Phys. Rev. B191150View full textAdd to dashboardCite

“…Of specific interest, intermetallic compounds in the vicinity of Stoner limit 1 exhibit exotic magnetic properties, such as nearly or weakly ferromagnetic Fermi liquid behavior, due to their strongly correlated d electrons. Particular attention has been paid to those systems containing both 4f local moments and highly correlated conduction electrons due to the rich phases result from the interactions between 4f and d electrons; among such materials, the RFe 2 Zn 20 compounds, which belong to the large RT 2 Zn 20 (R=Rare Earth elements, Y and U; T=Fe, Co, Ni, Ru, Rh, Os, Ir and Pt) series [2][3][4][5][6][7] , provide an ideal experimental platform, not only because they show various magnetic properties but also because they can be easily substituted on a number of unique crystallographic sites 3,4,[8][9][10] . RT 2 Zn 20 crystallizes in Fd3m space group, the nearest and next nearest neighbors of R and T atoms are all Zn.…”

Unusual signatures of the ferromagnetic transition in the heavy fermion compoundUMn2Al20

“…Introduction UMn 2 Al 20 , UV 2 Al 20 and UMo 2 Al 20 are members of a new family of lanthanide and actinide compounds RT 2 M 20 (R=Ce, Yb, Gd,U; T=transition metal; M=Zn and Al) [1][2][3][4][5][6][7] . These compounds crystallize in the CeCr 2 Al 20 type cubic structure (F d -3 m) and display interesting features such as heavy fermion or intermediate valence behavior [4][5][6][7] . In this structure, every f -atom is surrounded by 16 zinc atoms in a nearly spherical array of cubic site symmetry, which leads to small crystal field splittings.…”