Tuning spin currents in collinear antiferromagnets and altermagnets

This is the authors' abstract. We don't add key points for this paper.

Spin-current generation through nonrelativistic spin splittings, found in uncompensated magnets and <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:mi>d</a:mi> </a:math> -wave altermagnets (AMs), is desirable for low-power spintronics. Such spin currents, however, are symmetry forbidden in conventional collinear antiferromagnets and higher-order AMs. Using spin-point-group analysis, we demonstrate that finite spin currents can be induced in these materials via magnetoelectric-, piezomagnetic-, and piezomagnetoelectric-like couplings. We utilize electric fields, strain, and their combinations to drive symmetry-lowering phase transitions into uncompensated magnetic or <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"> <b:mi>d</b:mi> </b:math> -wave AM states, thereby enabling finite spin conductivity in a broader class of magnetic materials. We further substantiate this framework using density functional theory and Boltzmann transport calculations on representative magnetic materials— <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"> <c:mrow> <c:msub> <c:mi>KV</c:mi> <c:mn>2</c:mn> </c:msub> <c:msub> <c:mi>Se</c:mi> <c:mn>2</c:mn> </c:msub> <c:mi mathvariant="normal">O</c:mi> </c:mrow> <c:mo>,</c:mo> <c:mo> </c:mo> <c:msub> <c:mi>RuF</c:mi> <c:mn>4</c:mn> </c:msub> <c:mo>,</c:mo> <c:mo> </c:mo> <c:mrow> <c:msub> <c:mi>Cr</c:mi> <c:mn>2</c:mn> </c:msub> <c:msub> <c:mi mathvariant="normal">O</c:mi> <c:mn>3</c:mn> </c:msub> </c:mrow> <c:mo>,</c:mo> <c:mo> </c:mo> <c:msub> <c:mi>FeS</c:mi> <c:mn>2</c:mn> </c:msub> </c:math> , and <f:math xmlns:f="http://www.w3.org/1998/Math/MathML"> <f:msub> <f:mi>MnPSe</f:mi> <f:mn>3</f:mn> </f:msub> </f:math> —spanning these different cases. The charge-to-spin conversion and spin-splitter ratio reaches up to almost 100% via uncompensated magnetism and about 40% via <g:math xmlns:g="http://www.w3.org/1998/Math/MathML"> <g:mi>d</g:mi> </g:math> -wave AM under realistic conditions, highlighting the effectiveness of this approach for efficient spin-current generation.