Magnetoelectric domain engineering from micrometer to Ångstrøm scales

The functionality of magnetoelectric multiferroics depends on the formation, size, and coupling of their magnetic and electric domains. Knowing the parameters guiding these criteria is a key effort in the emerging field of magnetoelectric domain engineering. Here we show, using a combination of piezoresponse-force microscopy, nonlinear optics, and x-ray scattering, that the correlation length setting the size of the ferroelectric domains in the multiferroic hexagonal manganites can be engineered from the micron range down to a few unit cells under the substitution of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:msup><a:mrow><a:mi>Mn</a:mi></a:mrow><a:mrow><a:mn>3</a:mn><a:mo>+</a:mo></a:mrow></a:msup></a:math> ions with <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:msup><b:mrow><b:mi>Al</b:mi></b:mrow><b:mrow><b:mn>3</b:mn><b:mo>+</b:mo></b:mrow></b:msup></b:math> ions. The magnetoelectric coupling mechanism between the antiferromagnetic <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"><c:msup><c:mrow><c:mi>Mn</c:mi></c:mrow><c:mrow><c:mn>3</c:mn><c:mo>+</c:mo></c:mrow></c:msup></c:math> order and the distortive-ferroelectric order remains intact even at substantial replacement of <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"><d:msup><d:mrow><d:mi>Mn</d:mi></d:mrow><d:mrow><d:mn>3</d:mn><d:mo>+</d:mo></d:mrow></d:msup></d:math> by <e:math xmlns:e="http://www.w3.org/1998/Math/MathML"><e:msup><e:mrow><e:mi>Al</e:mi></e:mrow><e:mrow><e:mn>3</e:mn><e:mo>+</e:mo></e:mrow></e:msup></e:math>. Hence, chemical substitution proves to be an effective tool for domain-size engineering in one of the most studied classes of multiferroics. Published by the American Physical Society 2024