Giant Magnetostriction in Ferrimagnetic SmFe ₅ As ₃

Magnetostrictive materials are of interest not only from a fundamental perspective but also for their potential applications, spanning spintronics to energy harvesting. A new magnetostrictive material-SmFe₅As₃-reveals a complex interplay between magnetostriction, magnetic properties, and the crystal structure behavior. The ground state of SmFe₅As₃ is ferrimagnetic, as evidenced by magnetic susceptibility data, band-structure calculations, and XANES measurements. At <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics> <mml:mrow><mml:msub><mml:mi>T</mml:mi> <mml:mrow><mml:mi>m</mml:mi> <mml:mn>1</mml:mn></mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>28</mml:mn> <mml:mo>±</mml:mo> <mml:mn>4</mml:mn></mml:mrow> <mml:annotation>$T_{m1} = 28 \pm 4$</mml:annotation></mml:semantics> </mml:math> K, part of the Fe sublattice reorients, transitioning into a ferromagnetic state. This is followed by an entrance into the paramagnetic state at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics> <mml:mrow><mml:msub><mml:mi>T</mml:mi> <mml:mrow><mml:mi>m</mml:mi> <mml:mn>2</mml:mn></mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>76</mml:mn> <mml:mo>±</mml:mo> <mml:mn>4</mml:mn></mml:mrow> <mml:annotation>$T_{m2} = 76 \pm 4$</mml:annotation></mml:semantics> </mml:math> K. The effects observed in the magnetic measurements are accompanied by structural phase transitions. All three phases-below <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics><mml:msub><mml:mi>T</mml:mi> <mml:mrow><mml:mi>m</mml:mi> <mml:mn>1</mml:mn></mml:mrow> </mml:msub> <mml:annotation>$T_{m1}$</mml:annotation></mml:semantics> </mml:math> , between <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics><mml:msub><mml:mi>T</mml:mi> <mml:mrow><mml:mi>m</mml:mi> <mml:mn>1</mml:mn></mml:mrow> </mml:msub> <mml:annotation>$T_{m1}$</mml:annotation></mml:semantics> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics><mml:msub><mml:mi>T</mml:mi> <mml:mrow><mml:mi>m</mml:mi> <mml:mn>2</mml:mn></mml:mrow> </mml:msub> <mml:annotation>$T_{m2}$</mml:annotation></mml:semantics> </mml:math> , and above <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics><mml:msub><mml:mi>T</mml:mi> <mml:mrow><mml:mi>m</mml:mi> <mml:mn>2</mml:mn></mml:mrow> </mml:msub> <mml:annotation>$T_{m2}$</mml:annotation></mml:semantics> </mml:math> -are described by the same structural motif of the UCr₅P₃ type (monoclinic space group <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics><mml:mrow><mml:mi>P</mml:mi> <mml:msub><mml:mn>2</mml:mn> <mml:mn>1</mml:mn></mml:msub> <mml:mo>/</mml:mo> <mml:mi>m</mml:mi></mml:mrow> <mml:annotation>$P2_1/m$</mml:annotation></mml:semantics> </mml:math> ), differing only in the degree of deformation of the Fe-As framework. The new material exhibits giant magnetostriction of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics><mml:mrow><mml:mn>2500</mml:mn> <mml:mo>×</mml:mo> <mml:msup><mml:mn>10</mml:mn> <mml:mrow><mml:mo>-</mml:mo> <mml:mn>6</mml:mn></mml:mrow> </mml:msup> </mml:mrow> <mml:annotation>$2500 \times 10^{-6}$</mml:annotation></mml:semantics> </mml:math> . Dilatometry measurements on a SmFe₅As₃ single crystal indicate strongly diverse behavior, exhibiting not only negative, but also zero, as well as positive thermo-elastic effects.