A high-pressure ultrasonic investigation of the Néel transition in a Cr + 0.07 at.% Ir alloy single crystal

• Published in: Journal of physics. Condensed matter 1996-05, Vol.8 (22), p.4045-4054
• Main Authors: Martynova, J, Alberts, H L, Smit, P
• Format: Article
• Language: English
• Subjects: Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Magnetic phase boundaries (including magnetic transitions, metamagnetism, etc.); Magnetic properties and materials; Magnetically ordered materials: other intrinsic properties; Metals. Metallurgy; Physics
• ISSN: 0953-8984; 1361-648X
• DOI: 10.1088/0953-8984/8/22/008

Measurements of the ultrasonic wave velocity, ultrasonic attenuation, thermal expansion and electrical resisitivity of a Cr+0.07 at.% Ir alloy single crystal are reported as functions of temperature through the Neel point. Ultrasonic wave velocities were also measured as a function of temperature at different constant applied pressures and as a function of pressure at different constant temperatures. The pressure derivative of the Neel temperature corresponds closely to that observed for pure Cr and for several other dilute Cr alloys exhibiting a phase transition from an incommensurate spin-density wave to a paramagnetic phase at the Neel point. Hysteresis effects were observed in the temperature and pressure dependences of the ultrasonic wave velocity below the Neel temperature. These effects probably originate from a difference in the antiferromagnetic domain pattern existing in the alloy on cooling or heating through the Neel transition. No firm conclusions could be reached on whether the addition of 0.07 at.% Ir to Cr is enough to drive the first-order Neel transition of Cr to a second-order one.