ABSTRACT
Spin caloritronics [1–3] focuses on the study of the interaction between the charge and spin degrees of freedom with heat currents, this area bridges two very active fields of research: thermoelectricity and spintronics, which have the potential to harvest and reduce the energy consumption of modern logic devices. Thermoelectric phenomena emerge from the interaction between heat and charge, manifesting itself as a coupled transport of heat and electricity in electrically conductive materials [4]. Meanwhile, spintronics deals with the fundamental role of the spin of the electron in solid state physics and its potential applications [5, 6]. The pioneering work of Johnson and Silsbee in 1987 [7] started the field of spin caloritronics; they performed a theoretical study to include spin transport in the description of the thermoelectric effect at the interface of a heterostructure comprising a junction of a ferromagnetic and a normal metal layer (a detailed description of their thermodynamic theory is given in Chapter 5, Volume 1). Despite this initial effort, the activity in the spin caloritronics field remained low for many years with only a few experimental studies in metallic magnetic multilayers [8, 9], mainly related to the study of giant magnetoresistive effects [10, 11]. It was not until recently that the field gained renewed interest, mainly after the discovery of the spin Seebeck effect (SSE) by Uchida and co-workers in 2008 [12, 13], demonstrating that spin currents can be thermally generated from a ferromagnetic film into a non-magnetic metal attached and electrically detected by the inverse spin Hall effect, this effect is also regarded as a thermal spin pumping effect [14, 15].
