Magnetocaloric Properties of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:msub><mml:mi>R</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:msub><mml:mi>Ga</mml:mi><mml:mn>5</mml:mn></mml:msub><mml:msub><mml:mrow><mml:mrow><mml:mi mathvariant="normal">O</mml:mi></mml:mrow></mml:mrow><mml:mn>12</mml:mn></mml:msub></mml:math> (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:mi>R</mml:mi><mml:mo>=</mml:mo><mml:mtext>Tb, Gd, Nd, Dy</mml:mtext></mml:math>)
Markus Kleinhans, K. Eibensteiner, J. Leiner, C. Resch, Lukas Worch, Marc A. Wilde, J. Spallek, A. Regnat, C. Pfleiderer
Abstract
We report the characteristic magnetic properties of several members of the family of rare-earth garnets, ${\mathrm{Gd}}_{3}{\mathrm{Ga}}_{5}{\mathrm{O}}_{12}$ (GGG), ${\mathrm{Dy}}_{3}{\mathrm{Ga}}_{5}{\mathrm{O}}_{12}$, ${\mathrm{Tb}}_{3}{\mathrm{Ga}}_{5}{\mathrm{O}}_{12}$, and ${\mathrm{Nd}}_{3}{\mathrm{Ga}}_{5}{\mathrm{O}}_{12}$, and compare their relative potential utility for magnetocaloric cooling, including their minimal adiabatic demagnetization refrigeration (ADR) temperatures and relative cooling parameters. A main objective of this work concerns the identification of potential improvements over the magnetocaloric properties of GGG for use in low-temperature ADR cryostats. Using ${\mathrm{Tb}}^{+3}$ and ${\mathrm{Dy}}^{+3}$ at the rare-earth site offers, in principle, a higher saturation magnetization and ${\mathrm{Nd}}^{+3}$ gives a lower de Gennes factor and therefore potentially reduced magnetic transition temperatures, limiting the useful temperature range. Our results show that ${\mathrm{Dy}}_{3}{\mathrm{Ga}}_{5}{\mathrm{O}}_{12}$ yields an optimal relative cooling parameter at low applied fields and low limiting temperatures, which would allow for the design of more efficient ADR cryostats.