12-15 July 2011
Saint George Hotel
Africa/Johannesburg timezone
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Magnetic behavior of the Cr-Al alloys system round the triple point concentration

Presented by Prof. Aletta PRINSLOO on 13 Jul 2011 from 17:00 to 19:00
Type: Poster Presentation
Session: Poster1
Track: Track A - Condensed Matter Physics and Material Science


<p>Recent measurements on an antiferromagnetic (AFM) Cr<sub>0.978</sub>Al<sub>0.022</sub> alloy single crystal suggest that the triple point (TP) on the magnetic phase diagram (MPD) might be a special type of critical point. This suggestion is further investigated here through electrical resistivity and specific heat measurements on a series of Cr<sub>1-x</sub>Al<sub>x</sub> alloy single crystals with x around the triple point concentration (x<sub>c</sub>). Néel temperatures (T<sub>N</sub>), obtained from the resistivity measurements, indicate that x<sub>c</sub> ≈ 0.02 is situated at the position of a rather sharp and deep minimum of the AFM-paramagnetic phase transition line on the T - x MPD. The minimum is deeper than that generally accepted for this alloy system. The Sommerfeld electronic specific heat coefficient, obtained from the specific heat measurements, shows an interesting aspect. The Sommerfeld electronic specific heat coefficient as function of Al concentration peaks relatively sharply at x<sub>c</sub>, an aspect for which the explanation is two-fold: either the phase boundary line separating the incommensurate (I) and commensurate (C) spin-density-wave (SDW) phases on the MPD, starts at the TP and reaches T = 0 K vertically below this point, or the TP itself is situated close to T = 0 K. It is reasoned that the latter seems a more likely possibility, making this system unique in exhibiting a critical point at 0 K where ISDW, CSDW and paramagnetic (P) phases coexist.

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Short Paper



Room: Asteria

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