Metamagnetism, Multiple Magnetic Transitions and Wide Temperature Range Magnetocaloric Effect in Dy{sub 6.5}Co{sub 2}Si{sub 2.5} Alloy

• Published in: Journal of superconductivity and novel magnetism Vol. 32; no. 5
• Main Authors: Arun, K., Rashid, T. P., Curlik, Ivan, Ilkovic, Sergej, Reiffers, Marian, Dzubinska, Andrea, Nagalakshmi, R.
• Format: Journal Article
• Language: English
• Published: United States 15.05.2019
• Subjects: ANTIFERROMAGNETISM; COBALT COMPOUNDS; DYSPROSIUM COMPOUNDS; MAGNETIC FIELDS; MAGNETIC PROPERTIES; MAGNETIZATION; MAGNETORESISTANCE; MATERIALS SCIENCE; SILICON COMPOUNDS; TERNARY ALLOY SYSTEMS; THERMODYNAMICS; TRANSITION TEMPERATURE
• ISSN: 1557-1939; 1557-1947

We report the structure, magnetic, thermodynamic, transport, and magnetocaloric properties of Dy{sub 6.5}Co{sub 2}Si{sub 2.5} alloy. It shows that this alloy has been formed in three phases viz., Dy{sub 5}Si{sub 3}, Dy{sub 3}Co{sub 2.2}Si{sub 1.8}, and Dy{sub 3}Co with four successive magnetic transitions named as T{sub 1}, T{sub 2}, T{sub 3},T{sub 4}, at 43, 74.7, 90.5, and 132.4 K, respectively. The magnetic measurements display competing ferromagnetic and antiferromagnetic interactions in the alloy. At 2.5 K, the alloy exhibits hard ferromagnetic properties with a coercive field of 0.8 T. Metamagnetism is also evidenced in the isothermal magnetization measurements. The Arrot plot shows that this material undergoes first-order magnetic transitions below 47 K, and above which, magnetic transitions are of second order. The four successive magnetic transitions together with competing magnetic interactions give rise to a broadened magnetocaloric effect (MCE) peak with temperature width of ΔT = 83.8 and 93.2 K and consequently a large RC value of 474 and 739 J/kg, for a magnetic field change of 0–5 and 0–7 T, respectively. Additionally, it is found that the alloy exhibits negative magnetoresistance and attains a value of − 11 and − 7% at 2.5 and 50 K, respectively, in applied magnetic field of 9 T. Thus, the peculiar magnetic and magnetocaloric properties make the Dy{sub 6.5}Co{sub 2}Si{sub 2.5} alloy promising not only for low-temperature magnetic refrigeration but also for fundamental study perspectives.