http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Ho, Ping-Luen,Yu, Chu-Ping,Zhang, Qiqi,Song, Kyung,Buban, James P.,Choi, Si-Young,Dunin-Borkowski, Rafal E.,Mayer, Joachim,Tai, Nyan-Hwa,Zhu, Jing,Jin, Lei,Zhong, Xiaoyan Elsevier 2018 Ultramicroscopy Vol.193 No.-
<P><B>Abstract</B></P> <P>Superexchange-based magnetic coupling of the two <I>B</I>-site cations in rock-salt-ordered double perovskite oxides is extremely sensitive to the cation ratio and degree of order. However, as a result of the limited spatial resolution of most magnetic characterization techniques, it is challenging to establish a direct relationship between magnetic properties and structure in these materials, including the effects of elemental segregation and cation disorder. Here, we use electron energy-loss magnetic chiral dichroism together with aberration-corrected electron microscopy and spectroscopy to record magnetic circular dichroism (MCD) spectra at the nm scale, in combination with structural and chemical information at the atomic scale from the very same region. We study nanoscale phases in ordered Sr<SUB>2</SUB>[Fe][Re]O<SUB>6</SUB>, ordered Sr<SUB>2</SUB>[Fe][Fe<SUB>1/5</SUB>Re<SUB>4/5</SUB>]O<SUB>6</SUB> and disordered Sr[Fe<SUB>4/5</SUB>Re<SUB>1/5</SUB>]O<SUB>3</SUB> individually, in order to understand the role of cation ratio and order on local magnetic coupling. When compared with ordered Sr<SUB>2</SUB>[Fe][Re]O<SUB>6</SUB>, we find that antiferromagnetic Fe<SUP>3+</SUP>-O<SUP>2−</SUP>-Fe<SUP>3+</SUP>superexchange interactions arising from an excess of Fe suppress the MCD signal from Fe cations in ordered Sr<SUB>2</SUB>[Fe][Fe<SUB>1/5</SUB>Re<SUB>4/5</SUB>]O<SUB>6</SUB>, while dominant Fe<SUP>3+</SUP>-O<SUP>2−</SUP>-Fe<SUP>3+</SUP>antiferromagnetic coupling in disordered Sr[Fe<SUB>4/5</SUB>Re<SUB>1/5</SUB>]O<SUB>3</SUB> leads to a decrease in MCD signal down to the noise level. Our work demonstrates a protocol that can be used to correlate crystallographic, electronic and magnetic information in materials such as Sr<SUB>2</SUB>Fe<SUB>1+</SUB> <I> <SUB>x</SUB> </I>Re<SUB>1-</SUB> <I> <SUB>x</SUB> </I>O<SUB>6</SUB>, in order to provide insight into structure-property relationships in double perovskite oxides at the atomic scale.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Local measurements of magnetic circular dichroism, atomic arrangement, cation order, chemical state and elemental distribution from the very same region provide an improved understanding of structure-property relationships at the nm scale in double perovskites with different structural complexities. </LI> <LI> Antiferromagnetic Fe<SUP>3+</SUP>-O<SUP>2−</SUP>-Fe<SUP>3+</SUP>superexchange interactions arising from an excess of Fe suppress the magnetic circular dichroism signal from Fe cations in ordered Sr<SUB>2</SUB>[Fe][Fe<SUB>1/5</SUB>Re<SUB>4/5</SUB>]O<SUB>6</SUB>, when compared with ordered Sr<SUB>2</SUB>[Fe][Re]O<SUB>6</SUB>. </LI> <LI> Dominant Fe<SUP>3+</SUP>-O<SUP>2−</SUP>-Fe<SUP>3+</SUP>antiferromagnetic coupling in disordered Sr[Fe<SUB>4/5</SUB>Re<SUB>1/5</SUB>]O<SUB>3</SUB> leads to a decrease in magnetic circular dichroism signal down to the noise level. </LI> </UL> </P>