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|Type:||Artigo de periódico|
|Title:||Thermal Expansion And Magnetovolume Effects In The Heavy-fermion System Ce2rhin8|
|Abstract:||We present the results of thermal expansion α(T), nagnetostriction λ(H,T), and specific-heat Cp(T) measurements made on the heavy-fermion antiferromagnet Ce2RhIn8. The effects of magnetic order are clearly evident as anomalies in α(T) at T N=2.8 K and at Tm = 1.65 K. Cp(T) data indicate that the upper transition corresponds to the onset of long-range antiferromagnetic order while the lower transition involves only a subtle rearrangement of the ordered state. Both Cp/T and α/T grow with decreasing temperature below 20 K in a manner consistent with Kondo renormalization. Kondo interactions appear to be responsible for the large electronic Grüneisen parameter which extrapolates to ωe ≈ 48 as T→0, while the characteristic Kondo energy is TK ≈ 10 K as determined from the Cp/T ratio at TN. Above 20 K α(T) is dominated by crystalline-electricfield (CEF) effects. The data are consistent with a CEF level scheme consisting of excited γ 7 (1) and γ6 doublets lying 71±6 K and 195±10 K above a γ7 (2) ground state. In the paramagnetic state (T > TN) the volume magnetostriction follows a simple scaling law, λ∝[H/(T+ Tλ)] 2. The scaling parameter Tλ=5 K is consistent with the Kondo temperature determined from α(T) and Cp(T) data. Analysis of λ(H,T) data also indicates that the magnetic and electronic energy scales associated with the Kondo state in Ce2RhIn8 are equivalent. These thermodynamic data indicate that the physical properties of Ce2RhIn8 result from competition between magnetic exchange, Kondo, and CEF interactions.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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