Magnetocaloric and magnetotransport properties ofR2Ni2Sncompounds (R=Ce, Nd, Sm, G

Abstract

We report a detailed magnetic, magnetocaloric, and magnetotransport study on R 2 Ni 2 Sn compounds with different rare earths. The magnetic state of these compounds is found to be complex because of the coexistence of ferromagnetic and antiferromagnetic components. These compounds show phenomena such as multiple magnetic transitions, nonsaturation of magnetization, and metamagnetic transitions. Analysis of the zero-field heat capacity data shows that the magnetic entropy is less than the theoretical value, indicating the presence of some moment on Ni. Schottky anomaly is present in the magnetic heat capacity data of Sm 2 Ni 2 Sn. The temperature variation of magnetocaloric effect reflects the magnetization behavior. Tb 2 Ni 2 Sn and to a less extent Gd 2 Ni 2 Sn show oscillatory magnetocaloric effect. The variation of magnetocaloric effect is correlated with the ferromagnetic-antiferromagnetic phase coexistence. The electrical resistivity analysis has shown that the electron-magnon scattering is prominent at low temperature, while phonon scattering modified by the s-d interaction is crucial at high temperatures. The magnetoresistance is very large in Ce 2 Ni 2 Sn and shows a quadratic dependence on the field, implying the role of spin fluctuations in determining the transport behavior. Large magnetoresistance has been observed in other compounds as well.

Study of the magnetic properties and magnetocaloric effect in RCo2B2 (R = Tb, Dy and Ho) compounds

“…Whereas, a normal MCE was observed under higher magnetic field change which is related to the field-induced matamagnetic transition from AFM to FM state. The similar behaviors were also observed in recently reported TbNiAl 4 [42], Gd 2 Ni 2 Sn [43] and DySb [44] compounds. For R ¼ Dy and Ho, a large reversible MCE was observed which is related to a second order magnetic transition from PM to FM.…”

Excellent magnetocaloric properties of melt-extracted Gd-based amorphous microwires

“…A main goal for making this technology possible is to seek materials that are cost-effective and exhibit large magnetic entropy change (DS M ) over a wide temperature range, namely a large refrigerant capacity (RC). [4][5][6][7][8][9][10][11][12][13] The RC is a measure of the amount of heat transfer between the cold and hot reservoirs in an ideal refrigeration cycle, which depends not only on the magnitude of DS M but also on its temperature dependence (e.g., the full width at half maximum of the DS M (T) peak). 4,14 The existing magnetocaloric materials are far from ideal due to the limitations of their intrinsic structure and properties.…”

“…1,3,4,9,18 In addition, hysteretic losses associated with the FOMT are usually very large and therefore detrimental to the RC, whereas these effects are very small or negligible in the case of the SOMT materials. 4,18 In this context, it would be desirable to engineer peculiar SOMT materials 1,[3][4][5]7,9 or composites 6,[9][10][11][12][13] that undergo multiple SOMTs to exhibit large RC for active magnetic refrigeration (AMR) applications. From a cooling application perspective, it is noted that a magnetic refrigerator acquires a higher amount of heat absorption/extraction per volume than in a conventional gas-based cooling system.…”

Magnetic, magnetocaloric and magnetotransport properties of RSn1+xGe1−x compounds (R=Gd, Tb, and Er; x=0.1)

“…Furthermore, it can be seen that among these three compounds, TbSnGe exhibits the largest thermomagnetic irreversibility (between ZFC and FCW data), which is attributed to the pinning of domain walls [7][8][9]. It is well known that the width of the domain wall in a ferromagnet is directly proportional to the magnetic ordering temperature (T ord ) as given by the equation…”