Multiple ordered phases in the filled skutterudite compoundPrOs4As12

Abstract

Magnetization, specific heat, and electrical resistivity measurements were made on single crystals of the filled skutterudite compound PrOs4As12. Specific heat measurements indicate an electronic specific heat coefficient γ ∼ 50−200 mJ/mol K 2 at temperatures 10 K ≤ T ≤ 18 K, and ∼ 1 J/mol K 2 for T ≤ 1.6 K. Magnetization, specific heat, and electrical resistivity measurements reveal the presence of two, or possibly three, ordered phases at temperatures below ∼ 2.3 K and in fields below ∼ 3 T. The low temperature phase displays antiferromagnetic characteristics, while the nature of the ordering in the other phase(s) has yet to be determined.

Field-dependent ordered phases and Kondo phenomena in the filled skutterudite compound PrOs4As12

“…Two kinks in M(H), denoted H 1 and H 2 , were found to be suppressed toward lower field with increasing T. The dc magnetic susceptibility dc (T), reported in ref. 1 and shown in Fig. 4 Inset, displays a clear peak at T ϭ 2.3 K, indicative of AFM ordering, consistent with the neutron-scattering measurement reported herein.…”

“…Neutron diffraction measurements of PrOs 4 As 12 in zero field confirm that the ground state is AFM, with T N ϭ 2.28 K. C(H, T) and (H, T) data can be identified with transitions between two ordered phases and yield an H-T phase diagram similar to that inferred from the M(H, T) data previously reported (1). The T dependence of in the AFM ground state is consistent with the scattering of electrons by magnons with a gapped spectrum.…”

“…The order parameter of the sample in the AFM phase was determined by measuring the T dependence of the magnetic intensity at 2 ϭ 17.9°in the range 0.5-3.4 K. Fig. 1b indicates a Néel temperature T N ϭ 2.28 K, in excellent agreement with magnetization measurements (1).…”

“…In zero field, it was found that A ϭ 128 mJ⅐K͞mol, n ϭ 3.2 Ϯ 0.1, and ␥ Ϸ 1 J͞mol⅐K 2 (1). As stated in ref.…”

“…These discrepancies are caused partly by measurement-dependent differences in the definitions of the various transitions and variations between samples, in addition to the fact that M(H,T) and C(H,T) measurements were performed on a collection of crystals. Nonetheless, it may be inferred from the strong peaks in C(T) that there are two bulk-phase transitions: PrOs 4 As 12 has an AFM ground state, a different ordered state OP2 at intermediate T and H, and a PM state at high T and H. Previously, features in M(H, T) and crystalline electric field considerations were argued to support an AFM ground state (1). Neutron scattering has now confirmed AFM order in this phase.…”