Transport phenomena in spin caloritronics

Abstract

The interconversion between spin, charge, and heat currents is being actively studied from the viewpoints of both fundamental physics and thermoelectric applications in the field of spin caloritronics. This field is a branch of spintronics, which has developed rapidly since the discovery of the thermo-spin conversion phenomenon called the spin Seebeck effect. In spin caloritronics, various thermo-spin conversion phenomena and principles have subsequently been discovered and magneto-thermoelectric effects, thermoelectric effects unique to magnetic materials, have received renewed attention with the advances in physical understanding and thermal/ thermoelectric measurement techniques. However, the existence of various thermo-spin and magneto-thermoelectric conversion phenomena with similar names may confuse non-specialists. Thus, in this Review, the basic behaviors, spin-charge-heat current conversion symmetries, and functionalities of spin-caloritronic phenomena are summarized, which will help new entrants to learn fundamental physics, materials science, and application studies in spin caloritronics.

High-throughput imaging measurements of thermoelectric figure of merit

“…To confirm the versatility of the LIT-based method, we performed the same measurements and thermal analyses with applying a magnetic field H (with the magnitude H) to the samples. Although the H dependence of the electron transport coefficients is small in typical metals, σ, κ, and S (Π) of ferromagnetic metals depend on the magnetization direction due to the anisotropic magnetoresistance, anisotropic magneto-thermal resistance, and anisotropic magneto-Seebeck (Peltier) effects, respectively [22]. Here, we show that the LIT-based method can be used for the simultaneous measurements of the anisotropic magneto-thermal resistance and anisotropic magneto-Seebeck and Peltier effects for many materials.…”

“…LIT is an active thermal imaging technique that allows the detection of the thermal response in a sample to a periodic external perturbation with high temperature resolution [12]. Although LIT was originally developed for nondestructive testing of electronic components [13], it has shown notable performance in the measurements of various properties including the Peltier coefficient [14], thermal diffusivity [15], magnetocaloric effects [16,17], magneto-thermoelectric effects [18][19][20][21][22], and thermo-spin effects [23,24]. Here, we show that LIT also enables simultaneous measurements of S and κ, allowing the rapid derivation of ZT with a single apparatus.…”

“…Since LIT is a noncontact thermal imaging technique, the thermoelectric and thermal transport properties of multiple materials can be measured at the same time without the disturbance of heat leakage through temperature probes. The proposed method can be easily extended to the measurements under magnetic fields, enabling the investigation of magnetothermal resistance [22] and magneto-thermoelectric effects.…”

Spin Seebeck Effect of Correlated Magnetic Molecules

“…Moreover, we would like to note that spin Seebeck effect due to electron transport is also referred to as the spin-dependent Seebeck effect, whereas the typical Seebeck effect in the case of magnetic contacts is referred to as spin-resolved Seebeck effect. 29,32 However, in our paper we adopt the notion introduced byŚwirkowicz et al 35 The Seebeck and spin Seebeck coefficients as a function of temperature and the position of the molecule's orbital level calculated for different values of exchange interaction J are shown in Fig. 8.…”

“…In fact, with the discovery of the spin Seebeck effect, 27 a new field of interest, namely spin caloritronics, have started blossoming. [28][29][30][31][32] It transpires that the interplay of charge, heat and spin gives rise to a rich behavior of the thermoelectric coefficients that are now spin-dependent. [33][34][35] In correlated magnetic nanostructures, such as e.g.…”