<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>G</mml:mi> </mml:math> -type antiferromagnetic ordering with strong anisotropic exchange interactions in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub>

Isovalent substitution of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:msup> <a:mrow> <a:mi>Ir</a:mi> </a:mrow> <a:mrow> <a:mn>4</a:mn> <a:mo>+</a:mo> </a:mrow> </a:msup> </a:math> with <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"> <b:msup> <b:mrow> <b:mi>Sn</b:mi> </b:mrow> <b:mrow> <b:mn>4</b:mn> <b:mo>+</b:mo> </b:mrow> </b:msup> </b:math> in perovskite <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"> <c:msub> <c:mi>SrIrO</c:mi> <c:mn>3</c:mn> </c:msub> </c:math> induces a metal-insulator transition accompanied with strong antiferromagnetic ordering. We performed resonant x-ray scattering to investigate the magnetism in <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"> <d:mrow> <d:msub> <d:mi>SrIr</d:mi> <d:mrow> <d:mn>0.8</d:mn> </d:mrow> </d:msub> <d:msub> <d:mi>Sn</d:mi> <d:mrow> <d:mn>0.2</d:mn> </d:mrow> </d:msub> <d:msub> <d:mi mathvariant="normal">O</d:mi> <d:mn>3</d:mn> </d:msub> </d:mrow> </d:math> . The <f:math xmlns:f="http://www.w3.org/1998/Math/MathML"> <f:mi>G</f:mi> </f:math> -type antiferromagnetic ordering with spin pointing along <g:math xmlns:g="http://www.w3.org/1998/Math/MathML"> <g:mi>c</g:mi> </g:math> axis was fully determined by azimuth-dependent elastic scattering. Dynamical magnetic excitation spectra were measured with resonant inelastic x-ray scattering. Strong magnetic exchange interactions were observed with magnon dispersing up to <h:math xmlns:h="http://www.w3.org/1998/Math/MathML"> <h:mrow> <h:mo>∼</h:mo> <h:mn>130</h:mn> <h:mspace width="0.16em"/> <h:mi>meV</h:mi> </h:mrow> </h:math> , and the anisotropy drives a large <j:math xmlns:j="http://www.w3.org/1998/Math/MathML"> <j:mrow> <j:mo>∼</j:mo> <j:mn>50</j:mn> <j:mspace width="0.16em"/> <j:mi>meV</j:mi> </j:mrow> </j:math> gap. With these results, we discuss the paramagnetic semimetallic behavior of the undoped <l:math xmlns:l="http://www.w3.org/1998/Math/MathML"> <l:msub> <l:mi>SrIrO</l:mi> <l:mn>3</l:mn> </l:msub> </l:math> .