12-15 July 2011
Saint George Hotel
Africa/Johannesburg timezone

Spin-density-wave behaviour of the (Cr<sub>100-x</sub>Al<sub>x</sub>)<sub>95</sub>Mo<sub>5</sub> alloy system

13 Jul 2011, 17:00


Poster Presentation Track A - Condensed Matter Physics and Material Science Poster1


Mr Blessed Muchono (University of Johannesburg)


Previous studies in our laboratory on the (Cr100-xAlx)95Mo5 alloy system through electrical resistivity and magnetoelastic measurements suggest that spin-density-wave (SDW) antiferromagnetism is fully suppressed down to 4 K in the concentration range 2.0 ≤ x ≤ 5.0 at.% Al. The current interest in quantum criticality in Cr and Cr alloy systems warrants further detailed investigation into this aspect. In this regard we report results of electrical resistivity, Seebeck coefficient and Sommerfeld electronic specific heat coefficient (obtained from specific heat measurements) for an extended alloy range 0 ≤ x ≤ 8.1 at.% Al. The Seebeck coefficient turns out to be a more sensitive parameter than electrical resistivity in obtaining magnetic phase transition temperatures for this alloy system, particularly for the commensurate (C) SDW phase region x ≥ 5.0 at.% Al. The electrical resistivity and Seebeck coefficient data depicts total suppression of AFM down to 2 K for 1.5 ≤ x ≤ 5.3 at.% Al. The results of Sommerfeld electronic specific heat coefficient confirms this finding, showing a sharp increase in the incommensurate (I) SDW phase up to x ≈ 1.5 at.% Al, roughly leveling off in the paramagnetic range 2.0 ≤ x ≤ 4.6 at.% Al, followed by a slow decreasing trend in the CSDW phase x ≥ 5.0 at.% Al. From the present study it appears that both points (x ≈ 1.5 at.% Al, T = 0 K) and (x ≈ 5.0 at.% Al, T = 0 K) are possible quantum critical points on the magnetic phase diagram of the (Cr100-xAlx)95Mo5 alloy system. It is then rather unique to have both ISDW-P and P-CSDW quantum critical points existing in the same alloy system.

Consider for a student <br> &nbsp; award (Yes / No)? Yes
Would you like to <br> submit a short paper <br> for the Conference <br> Proceedings (Yes / No)? No
Level (Hons, MSc, <br> &nbsp; PhD, other)? PhD

Primary author

Mr Blessed Muchono (University of Johannesburg)


Prof. Aletta Prinsloo (University of Johannesburg) Prof. Andre Strydom (University of Johannesburg) Dr Charles Sheppard (University of Johannesburg) Prof. Herman Alberts (University of Johannesburg)

Presentation Materials