Specific heat and thermal conductivity of UCu4+xAl8−x compounds

• Published in: Journal of the Korean Physical Society Vol. 62; no. 10; pp. 1567 - 1571
• Main Authors: Nasreen, F., Torikachvili, M. S., Kothapalli, K., Kohama, Y., Zapf, V. S., Nakotte, H.
• Format: Journal Article
• Language: English
• Published: Seoul The Korean Physical Society 2013; 한국물리학회
• Subjects: Mathematical and Computational Physics; Particle and Nuclear Physics; Physics; Physics and Astronomy; Theoretical; 물리학; Quantum critical point; Antiferromagnetic correlations; Non-Fermi-liquid scaling
• ISSN: 0374-4884; 1976-8524
• DOI: 10.3938/jkps.62.1567

We report on thermal conductivity and specific heat measurements for eight UCu 4+ x Al 8− x compounds (0 ≤ x ≤ 2.0) as a function of temperature and magnetic field. For this series of compounds, previous magnetic and transport studies indicated a transition from magnetic to a non-magnetic heavy fermion state near x cr ≈ 1.15. This paper presents supplementary specific heat and thermal conductivity studies. The ratio of the specific heat over temperature C/T data on the non magnetic compound with x cr ≈ 1.15 show logarithmic dependence with T, a hallmark of non-Fermi liquid (NFL) behavior due to the proximity of a quantum critical point. Compounds with higher Cu content ( x > x cr ) exhibit unusual temperature scaling in the specific heat possibly due to an increase in disorder between Cu and Al. Thermal conductivity data show stark contrast in the behaviors between the magnetic ( x = 0.5) and non-magnetic compound ( x = 1.75). Our results confirm that a simple free-electron picture is inadequate for the description of the low-temperature thermal conductivity properties in non-magnetic UCu 4+ x Al 8− x compounds.