Magnon-mediated electric current drag and nonlocal spin-Peltier effect in the ac regime

Electron-magnon coupling at the interface between a normal metal and a magnetically ordered insulator modifies the electrical conductivity of the normal metal, an effect known as spin-Hall magnetoresistance. It can also facilitate magnon-mediated electric current drag, the nonlocal electric current response of two normal metal layers separated by a magnetic insulator. Additionally, spin and heat transport are coupled both in the magnetic insulator and across the interfaces to normal metals. In this article, we present a theory of these spintronic and spin-caloritronic effects for time-dependent applied electric fields <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:mrow> <a:mi>E</a:mi> <a:mo>(</a:mo> <a:mi>ω</a:mi> <a:mo>)</a:mo> </a:mrow> </a:math> , with driving frequencies <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"> <b:mi>ω</b:mi> </b:math> up to the terahertz regime. Our model describes how the dominant transport mechanism, coherent or incoherent magnons, evolves with the driving frequency <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"> <c:mi>ω</c:mi> </c:math> .