Tunnel magneto-Seebeck effect

Abstract

The interplay of charge, spin and heat transport is investigated in the fascinating research field of spin caloritronics, the marriage of spintronics and thermoelectrics. Here, many new spin-dependent thermal transport phenomena in magnetic nanostructures have been explored in the recent years. One of them is the tunnel magneto-Seebeck (TMS) effect in magnetic tunnel junctions (MTJs) that has large potential for future nanoelectronic devices, such as nanostructured sensors for threedimentional thermal gradients, or scanning tunneling microscopes driven by temperature differences. The TMS describes the dependence of the MTJ's thermopower on its magnetic configuration when a thermal gradient is applied. In this review, we highlight the successful way from first observation of the TMS in 2011 to current ongoing developments in this research area. We emphasize on different heating techniques, material designs, applications, and additional physical aspects such as the role of the thermal conductivity of the barrier material. We further demonstrate the efficient interplay between ab initio calculations and experiments within this field, as this has led, e.g., to the detection of large TMS ratios in MTJs with half-metallic Heusler electrodes.

First-principles study of the anisotropic magneto-Peltier effect

“…In the present analysis, we focus on the intrinsic mechanism of the AMPE by applying the first-principles-based Boltzmann transport approach to bulk ferromagnets. This is because the AMPE (AMSE) discussed in this study occurs in bulk ferromagnets and does not require any interfaces, unlike other phenomena; e.g., the spindependent Seebeck and Peltier effects in magnetic nanostructures [24][25][26] and the magneto-Seebeck and Peltier effects in magnetic tunnel junctions [27][28][29].…”

Thermal Conductivity of Oxide Tunnel Barriers in Magnetic Tunnel Junctions Measured by Ultrafast Thermoreflectance and Magneto-Optic Kerr Effect Thermometry

“…Passing a heat current through an MTJ leads to further phenomena in which heat, charge, and spin transport are coupled, thereby increasing the number of potential spintronic applications. For example, the tunnel magneto-Seebeck (TMS) effect [4,5] refers to the change of the Seebeck coefficient of an MTJ depending on its magnetic configuration. Together with additional magnetothermoelectric effects, the TMS can be utilized, e.g., for three-dimensional sensing of temperature gradients in nanostructures.…”

Strain-induced enhancement of the Seebeck effect in magnetic tunneling junctions via interface resonant tunneling: Ab initio study

“…The heat-to-charge current conversion, namely, the Seebeck effect, in MTJs has been recently investigated both experimentally [6][7][8][9][10][11][12][13][14][15][16] and theoretically [17][18][19][20][21][22][23][24][25][26] , in which most studies have considered the tunnel magneto-Seebeck (TMS) ratio 27 , the thermoelectric analog of the tunnel magnetoresistance ratio. MTJs with a large Seebeck effect have potential not only to produce a large TMS ratio, but also to realize various applications such as thermal energy harvesting, thermoelectric cooling in nanoscale spintronic devices 27 , and scanning Seebeck tunneling microscopy 28,29 .…”