SAIP2012

Spin density wave behaviour in the (Cr₈₄Re₁₆)_100-yV_y system

11 Jul 2012, 08:40

20m

Oral Presentation Track A - Division for Condensed Matter Physics and Materials DCMPM2

Speaker

Mrs Bincy Susan Jacobs (University Of Johannesburg)

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

Yes

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

PhD

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

Yes

Abstract content <br> &nbsp; (Max 300 words)

The spin density wave (SDW) behaviour in the (Cr₈₄Re₁₆)_100-yV_y alloy system, with 4 ≤ y ≤ 14, was investigated using electrical resistivity (ρ), Seebeck coefficient (S) and specific heat (Cp) measurements as a function of temperature (T). For this alloy series ρ measurements reveal a clear anomaly at the Néel temperature (T_N), which can be ascribed to the opening up of the SDW energy gap and the corresponding decrease in charge carrier density on cooling through T_N [1]. The Seebeck coefficient is sensitive to the changes in the electronic structure and scattering mechanisms that are consequential to the antiferromagnetic phase [1]. An anomaly in the form of a hump in the vicinity of T_N is observed in the S(T) curves for samples with y = 5.7 and 8.5. On increasing y the magnitude of this anomaly is suppressed and the position of the hump shifts to lower temperatures, corresponding to a decrease in T_N. At low temperatures, a broad valley is observed for y = 4 and 5.7. On increasing y, this valley initially becomes more pronounced, but eventually weakens and becomes imperceptible in samples with y > 5.7. T_N(y) obtained from both ρ(T) and S(T) measurements indicate the existence of a possible quantum critical point at y ≈ 10.4. Signatures of quantum critical behaviour have also been linked to anomalies in the behaviour of the Sommerfeld electronic specific heat coefficient (γ) as a function of the tuning parameter [2]. γ is obtained from the low temperature Cp measurements and γ(y) for the (Cr₈₄Re₁₆)_100-yV_y alloy system also shows an anomaly in the vicinity of the putative quantum critical point.

[1] E. Fawcett et al., Rev. Mod. Phys. 66, 25 (1994).
[2] J. Takeuchi et al., J. Phys. Soc. Jpn. 49, 508 (1980)

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

Prof ARE Prinsloo, alettap@uj.ac.za, University Of Johannesburg

Presentation Materials

Paper

SJ__Paper_Final_Version.pdf

Peer reviewing

Paper

Accepted on 1 Dec 2014 by Ncholu Manyala

SJ__Paper_Final_Version_Revised.pdf