• Deng, H.
• Legut, Dominik
• Čermák, P.
• Franz, Christian
• Bauer, Andreas
• Schneidewind, Astrid
• Hansen, Ursula Bengaard
• Meven, Martin
• Schönmann, R.
• Fåk, B.
• Nemkovski, Kirill
• Stekiel, Michal
• Pfleiderer, Christian
• Weber, S.
• Kumar, V.

Abstract

<jats:p>We investigate the effect of structural deformation on the magnetic properties of orthorhombic <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:msub><a:mi>CePdAl</a:mi><a:mn>3</a:mn></a:msub></a:math> in relation to its tetragonal polymorph. Utilizing x-ray and neutron diffraction, we establish that the crystal structure has the <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:mrow><b:mi>C</b:mi><b:mi>m</b:mi><b:mi>c</b:mi><b:mi>m</b:mi></b:mrow></b:math> space-group symmetry and exhibits pseudotetragonal twinning. According to density functional calculations, the tetragonal-orthorhombic deformation mechanism has its grounds in the relatively small free enthalpy difference between the polymorphs, allowing either phase to be quenched, and fully accounts for the twinned microstructure of the orthorhombic phase. Neutron diffraction measurements show that orthorhombic <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"><c:msub><c:mi>CePdAl</c:mi><c:mn>3</c:mn></c:msub></c:math> establishes long-range magnetic order below <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"><d:mrow><d:msub><d:mi>T</d:mi><d:mi mathvariant="normal">N</d:mi></d:msub><d:mo>=</d:mo><d:mn>5.29</d:mn><d:mspace width="0.16em"/><d:mrow><d:mo>(</d:mo><d:mn>5</d:mn><d:mo>)</d:mo></d:mrow></d:mrow></d:math> K characterized by a collinear, antiferromagnetic arrangement of magnetic moments. Magnetic anisotropies of orthorhombic <g:math xmlns:g="http://www.w3.org/1998/Math/MathML"><g:msub><g:mi>CePdAl</g:mi><g:mn>3</g:mn></g:msub></g:math> arise from strong spin-orbit coupling as evidenced by the crystal-field splitting of the <h:math xmlns:h="http://www.w3.org/1998/Math/MathML"><h:mrow><h:mn>4</h:mn><h:mi>f</h:mi></h:mrow></h:math> multiplet, fully characterised with neutron spectroscopy. We discuss the potential mechanism of frustration posed by antiferromagnetic interactions between nearest neighbors in the tetragonal phase, which hinders the formation of long-range magnetic order in tetragonal <i:math xmlns:i="http://www.w3.org/1998/Math/MathML"><i:msub><i:mi>CePdAl</i:mi><i:mn>3</i:mn></i:msub></i:math>. We propose that orthorhombic deformation releases the frustration and allows for long-range magnetic order.</jats:p><jats:sec><jats:title/><jats:supplementary-material><jats:permissions><jats:copyright-statement>Published by the American Physical Society</jats:copyright-statement><jats:copyright-year>2024</jats:copyright-year></jats:permissions></jats:supplementary-material></jats:sec>

Topics

• density
• phase
• neutron diffraction
• deformation mechanism
• size-exclusion chromatography
• neutron spectroscopy
• twinned