SAIP2014

Magnetic and transport studies on Cr_100-<i>x</i>Ir_<i>x</i> alloy single crystals

9 Jul 2014, 17:10

1h 50m

D Ring ground level

Board: A.54

Poster Presentation Track A - Division for Physics of Condensed Matter and Materials Poster2

Speaker

Mr Pius Rodney Fernando (University of Johannesburg)

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

Yes

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>

An investigation of the physical properties of Cr_100-xIr_x alloy single crystals, with x = 0.7, 1.5, 2.0 and 2.5, were previously used to establish the magnetic phase diagram of Cr_100-xIr_x alloy system around triple point concentration [1] where the various magnetic phases co-exist. The present study extends these results by considering the temperature (T) dependence of the Seebeck coefficient (S), specific heat (C_p) and Hall coefficient (R_H) measurements, in addition to the electrical resistivity (ρ) [1]. Well defined anomalies were observed in the electrical resistivity ρ(T) curves of all the samples, due to the antiferromagnetic to paramagnetic phase transition on heating through the Néel temperature (T_N). The S(T) curves of the samples with x = 0.7, 1.5 and 2.0 also exhibit anomalies associated with T_N in the temperature range below 380 K. As the upper limit of temperature for the measurements was 380 K, the anomaly associated with T_N could not be observed for x = 2.5 alloy (T_N = 391.5 K). Contrary to what is normally expected [2] it is noted that the anomaly related to T_N is more prominent in the (ρ) curves than in the S(T) curves. (R_H) measurements carried out from 380 K down to 2 K in a constant magnetic field of 6 T, shows only weak anomalies at T_N for certain samples. The Sommerfeld coefficient (γ) is obtained by fitting C_p/T = γ + (β)T² to the low temperature C_p/T versus T² data. The γ values found for the present single crystal samples fits in well with the γ versus electron-to-atom (e/a) ratio curve previously published [3, 4] for certain Cr alloys.

[1].Martynova J et al. 1998 J. Magn. Magn. Mat 187 345
[2].Fawcett E et al.1994 Rev. Mod. Phys. 66 25
[3].Heiniger F 1966 Phys. Kondens. Materie 5 285
[4].Heiniger F et al. 1966 Phys. Kondens. Materie 5 243

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

ARE Prinsloo

alettap@uj.ac.za

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

PhD

Presentation Materials

Paper

CrIr_Single_Crystals_SAIP_2014_Final_Version_24-06-14.pdf

Peer reviewing

Paper

Accepted on 26 Jan 2015 by Steven Karataglidis

054ab.pdf