SAIP2016

Interplay of antiferromagnetic and Kondo effect in Ce₈Pd₂₄Al

5 Jul 2016, 16:10

1h 50m

Kramer Law building

Board: A.258

Poster Presentation Track A - Division for Physics of Condensed Matter and Materials Poster Session (1)

Speaker

Mr Aiman Bashir (University of the Western Cape)

Would you like to <br> submit a short paper <br> for the Conference <br> Proceedings (Yes / No)?

Yes

Main supervisor (name and email)<br>and his / her institution

Moise B. Tchoula Tchokonte; mtchokonte@uwc.ac.za; University of the Western Cape

Apply to be<br> considered for a student <br> &nbsp; award (Yes / No)?

Yes

Please indicate whether<br>this abstract may be<br>published online<br>(Yes / No)

Yes

Level for award<br>&nbsp;(Hons, MSc, <br> &nbsp; PhD, N/A)?

PhD

Abstract content <br> &nbsp; (Max 300 words)<br><a href="http://events.saip.org.za/getFile.py/access?resId=0&materialId=0&confId=34" target="_blank">Formatting &<br>Special chars</a>

The suppression of antiferromagnetic (AFM) order and Kondo effect in Ce₈Pd₂₄Al with the dilution of Ce with La is investigated by means of magnetic susceptibility, χ(T), magnetization, M(μ₀H), electrical resistivity, ρ(T), magnetoresistivity, MR, thermoelectric power, S(T), and thermal conductivity, λ(T) measurements. X – ray diffraction studies indicate a cubic AuCu₃ – type crystal structure for all compositions on the alloys series (Ce_1–x La_x)₈Pd₂₄Al. At high temperature, χ(T) follows the paramagnetic Curie – Weiss behavior with negative paramagnetic Weiss temperatures θ_p and effective magnetic moment μ_eff values in close agreement with the value of 2.54 μ_B expected for free Ce³⁺ - ion. The low temperature dc χ(T) data show an AFM anomaly associated with a Néel temperature T_N which decreases almost linearly from 4.2 K for x = 0 to 2.9 K for x = 0.2 alloys. For alloys in the concentration range of 0 ≤ x ≤ 0.3, ρ(T) is characterized by a coherent Kondo lattice scattering with a well-defined ρ(T) maximum at T_max = 9 K to 5.1 K for compositions in the range 0 ≤ x ≤ 0.3, while incoherent single – ion Kondo scattering prevail for the x ≥ 0.4 alloys. MR measurements on Ce diluted alloys are analyzed based on the calculations by Schlottmann for the Bethe – ansatz in the frame of the Coqblin – Schrieffer model and yields values of the Kondo temperature T_K and the effective moment of the Kondo ion μ_K. The decrease in T_K and T_max is described by the compressible Kondo lattice model. S(T) measurements are interpreted within the phenomenological resonance model giving values of the characteristic temperature T_CEF associated to crystal – electric field (CEF) effect. λ(T) data increase linearly with temperature from low temperature with T, while the reduced Lorentz number L/L₀ increase upon cooling and exhibit maxima at low temperature which decrease in magnitude with increased La content x.