Determination of the crystal field parameters in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Sm</mml:mi><mml:msub><mml:mi>Fe</mml:mi><mml:mn>11</mml:mn></mml:msub><mml:mi>Ti</mml:mi></mml:mrow></mml:math>
L.V.B. Diop, M. D. Kuz’min, Y. Skourski, Konstantin Skokov, Iliya Radulov, Oliver Gutfleisch
Abstract
The magnetization of $\mathrm{Sm}{\mathrm{Fe}}_{11}\mathrm{Ti}$ single crystals has been measured along the principal crystallographic directions in steady (14 T) and pulsed (43 T) magnetic fields. The fourfold symmetry axis [001] is an easy magnetization direction. The magnetization curves measured in directions perpendicular to [001] are remarkable in two ways: (i) They do not depend on orientation of $\mathbit{H}$ within the basal plane; (ii) at low temperature they are $\mathsf{S}$ shaped, with an inflection point at about 0.6 times saturation magnetization. These two facts enable us to conclude that three out of five crystal field parameters of $\mathrm{Sm}{\mathrm{Fe}}_{11}\mathrm{Ti}$ are negligibly small; only ${A}_{2}^{0}$ and ${A}_{6}^{0}$ are essentially nonzero. A comparison with an isomorphous compound ${\mathrm{DyFe}}_{11}\mathrm{Ti}$ reveals a dramatic disparity of their crystal fields, especially as regards ${A}_{4}^{4}$, nearly zero in $\mathrm{Sm}{\mathrm{Fe}}_{11}\mathrm{Ti}$ but outstandingly large in ${\mathrm{DyFe}}_{11}\mathrm{Ti}$.