Magnetoelastic and neutron-diffraction studies of Cr-Al-alloy single crystals

Critical behavior of a single-crystal (110) Cr near the Néel temperature

“…yielding T N = 314.55 K and α = 0.33 (A and B are some constants). The fit is fairly good but not as good as that found for a magnetization data with α = 0.5 [9]. A fragment of the H(T ) plot in the vicinity of T N including the data obtained for decreasing T (full symbols) is displayed in fig.…”

“…It is interesting to notice here that the values of β reported so far in the literature for chromium and its alloys agree with those found presently. For instance, Noakes et al estimated β = 0.3 for a single crystal Cr+0.2%V sample [10], Baran et al reported β ≈ 0.5 for single crystals of Cr + xAl (x = 1.2, 1.9 and 2.6 at%) [9], and Boshoff et al found β = 0.3-0.4 for a single crystal of Cr + yRu (y = 0.3, 0.5 at%) [11].…”

Magnetoelasticity of a Cr+2.2 at.% Al-alloy single crystal

“…5 K where the ultrasonic signal for this shear mode becomes very small, the results for cI1 and B are only shown up to this temperature. The broken curves in figures 1 and 2 represent the expected nonmagnetic behaviour and were obtained as previously [2] from the temperature dependences of the elastic constants [8] of a Cr + 5 at.% V crystal that remains paramagnetic at all temperatures. The magnetic contributions to the elastic constants are obtained by subtracting the measured values of the Cr + 2.2 at.% AI crystal from the broken curves in figures 1 and 2.…”

“…The magnetic phase diagram of this system contains four magnetic phases: the longitudinal (L) incommensurate (I) sDW phase, the transverse (T) ISDW phase, the commensurate (c) SDW phase and the paramagnetic (P) phase [l]. There exists a triple point on the magnetic phase diagram near 2 at.% AI and 130 K where the ISDW, CSDW and P phases coexist [1,2]. A plot of the magnetic Griineisen parameters as a function of AI concentration, determined from elastic constant and thermal expansion measurements on polycrystalline Cr-AI alloys [3], shows a gigantic peak centred at 2.2 at.% Al.…”

“…This is particularly so for magnetoelastic effects for which polycrystalline measurements give incomplete information concerning the influence of the SDW on the elastic properties. Elastic constant measurements on Cr-AI alloy single crystals containing 1.2, 1.9 and 2.6 at.% AI were recently reported [2]. A single crystal containing the critical concentration of 2.2 at.% A1 was unfortunately not studied and neither were magnetovolume effects in the above three Cr-AI-alloy single crystals.…”