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The anomalous Nernst effect (ANE), one of the thermomagnetic effects studied for a long time, has recently attracted renewed attention. The ANE, which originates from fictitious fields in momentum space, is essential for clarifying the interplay among heat, spin, and charge in magnets. Moreover, compared to the Seebeck effect, it has various benefits for application to high-efficiency energy-harvesting devices as it may provide much more simple lateral structure, higher flexibility, and much lower production cost. In this review, we discuss various topics related to the methods to modulate the ANE for its thermoelectric applications. In addition, we review strategies to design materials to obtain large ANE including Weyl magnets and thermoelectric devices for effectively utilizing the ANE.

The presence of the coupled spin and valley degrees of freedom makes silicene an important material for spintronics and valleytronics. Here we report a spin-valley filter effect in a silicene based antiferromagnetic/ferromagnetic junction. It is found that at zero Fermi level a valley locked bipolar spin filter effect is observed, where in a broad gate voltage range in one valley one spin (the other spin) electrons contribute to the current under the positive (negative) bias, but in the other valley the transport is forbidden. At the finite Fermi level a valley locked fully spin-polarized current can exist under both the positive and negative biases. Furthermore, at the high Fermi level by reversing the bias direction, the spin filter effect can switch to the valley filter effect. In addition, by changing the sign of the Fermi level, the spin polarization direction of the current can be reversed. If a temperature bias is applied, the spin-dependent Seebeck effect (SSE) always exists. With increasing the temperature bias, the system undergoes three regions: valley locked SSE, normal SSE and valley Seebeck effect. Moreover, by tuning the interlayer electric field, three phases: thermally induced valley locked spin filter effect, valley Seebeck effect and valley mixed Seebeck effect are observed.

Nonreciprocal transport plays a crucial role in various fundamental challenges and applications in the fields of physics and technology. Here, we investigate the thermal spin transport property of helimagnets using the Non-equilibrium Green’s Function method. Our results reveal that the spin currents driven by a temperature difference remain reciprocal in the absence of an external magnetic field and magnetic anisotropy. However, a nonreciprocal spin Seebeck effect arises when an external magnetic field or magnetic anisotropy is introduced in the system. Notably, the nonreciprocal effect can be amplified with increasing strength of the magnetic field or magnetic anisotropy. Furthermore, we demonstrate that this effect persists even in the presence of Gilbert damping. A detailed analysis highlights how the breaking of mirror symmetry contributes to asymmetries in magnon spin transmission, ultimately leading to nonreciprocal behavior.

Transverse thermoelectric conversion holds significant potential in addressing complex challenges faced by classical Seebeck/Peltier modules. A promising transverse thermoelectric phenomenon is the anomalous Nernst effect originating from nontrivial band structures in magnetic topological materials. However, the currently reported performance of the anomalous Nernst effect in topological materials, e.g., Co 2 MnGa, remains insufficient for practical thermoelectric applications. Here, we unveil an unconventional availability of the anomalous Nernst effect by integrating magnetic topological materials into artificially tilted multilayers, known to exhibit the structure-induced transverse thermoelectric conversion due to the off-diagonal Seebeck effect. Our experiments reveal that the transverse thermoelectric performance in Co 2 MnGa-based artificially tilted multilayers is improved through the hybrid action of the anomalous Nernst and off-diagonal Seebeck effects, with the magnetization-dependent performance modulation being one order of magnitude greater than the performance achievable with the anomalous Nernst effect alone. This synergy underscores the importance of hybrid transverse thermoelectric conversion and paves a way for advancing thermoelectric applications using magnetic materials. The anomalous Nernst effect is a key for transverse thermoelectric applications. Here, the authors show an intense performance improvement of the anomalous Nernst effect via hybrid actions with the off-diagonal Seebeck effect in artificial materials.

Enhancing the tunneling magneto-Seebeck (TMS) ratio and uncovering its underlying mechanism are greatly demanded in spin caloritronics. The magnitude and sign of the TMS effect depend on the type of atom and the stacking order of atoms at the interfaces. Herein, we demonstrate that TMS ratios can be effectively manipulated by altering heterogonous or homogeneous interface through decoration on the CoFeSi (001) surface inserted on the MgO insulating layers. The maximum TMS ratio of pure Co 2 /O termination is 4565% at 800 K. Notably, the TMS ratio of the FeSi/O termination has two peak values, of which the maximum could reach up to −3290% at 650 K. By comparing two different atom arrangements at the interface, we reveal that the sign and symbol of the TMS ratio can be controlled by the temperature and different atomic configurations at the Co 2 FeSi/MgO interface. Furthermore, the spin-Seebeck coefficient up to ∼150 µV/K is also possible when we select suitable terminations and temperatures. These findings will provide useful insights into how to control the sign and symbol of the TMS ratio and accordingly stimulate the development field of magneto-thermoelectric power and spin caloritronic devices based on the magneto-Seebeck effect in Heusler-based metallic multilayers.

We theoretically study the electrolyte Seebeck effect in the vicinity of a heated metal nanostructure, such as the cap of an active Janus colloid in an electrolyte, or gold-coated interfaces in optofluidic devices. The thermocharge accumulated at the surface varies with the local temperature, thus modulating the diffuse part of the electric double layer. On a conducting surface with non-uniform temperature, the isopotential condition imposes a significant polarization charge within the metal. Surprisingly, this does not affect the slip velocity, which takes the same value on insulating and conducting surfaces. Our results for specific-ion effects agree qualitatively with recent observations for Janus colloids in different electrolyte solutions. Comparing the thermal, hydrodynamic, and ion diffusion time scales, we expect a rich transient behavior at the onset of thermally powered swimming, extending to microseconds after switching on the heating.

The longitudinal spin Seebeck effect (LSSE) has been investigated in ZnFe 2 O 4 (ZFO) thin films on different substrates, such as Si (111), MgO (100), and SrTiO 3 (100). The LSSE voltage signal exhibited a linear dependence on the temperature difference between both sides of the samples. The spin Seebeck coefficients were highly sensitive to the thermal conductivities of the magnetic layer and substrate, with values from 3 nV/k to 110 nV/K. Charge currents ( J c ) and spin currents ( J s ) densities were estimated. J s values are similar for the samples deposited on MgO and STO. The saturation magnetic field for the LSSE signal was reached with a magnetic field lower than its bulk counterpart. These results were related to the lattice mismatch between the ZFO films and the substrate, the magnetic response, and the anisotropies present in the samples since a twofold in-plane anisotropy was observed for the sample deposited on Si, while the samples deposited on MgO and SrTiO 3 showed a fourfold in-plane anisotropy. Moreover, the presence of a notable perpendicular magnetic anisotropy in the thin films may be a consequence of the lattice mismatch and at the same time, it can cause the saturation in the LSSE voltage hysteresis loop measured as a function of the external magnetic be reached with a low magnetic field.

When a thermoelectric (TE) material is deposited with a secondary TE material, the total Seebeck coefficient of the stacked layer is generally represented by a parallel conductor model. Accordingly, when TE material layers of the same thickness are stacked vertically, the total Seebeck coefficient in the transverse direction may change in a single layer. Here, an abnormal Seebeck effect in a stacked two‐dimensional (2D) PtSe2/PtSe2 homostructure film, i.e., an extra in‐plane Seebeck voltage is produced by wet‐transfer stacking at the interface between the PtSe2 layers under a transverse temperature gradient is reported. This abnormal Seebeck effect is referred to as the interfacial Seebeck effect in stacked PtSe2/PtSe2 homostructures. This effect is attributed to the carrier‐interface interaction, and has independent characteristics in relation to carrier concentration. It is confirmed that the in‐plane Seebeck coefficient increases as the number of stacked PtSe2 layers increase and observed a high Seebeck coefficient exceeding ≈188 µV K−1 at 300 K in a four‐layer‐stacked PtSe2/PtSe2 homostructure. A novel strategy to increase the Seebeck coefficient of 2D PtSe2 films by stacking the same PtSe2 layer onto each other as stacked PtSe2/PtSe2 homostructures via a wet‐transfer method is demonstrated. The Seebeck coefficient increases significantly with increasing number of stacking films in a PtSe2/PtSe2 homostructure for a four‐stacked homostructure due to the carrier‐interface interaction under the longitudinal temperature gradient.

In this paper, we describe the possibility of using the energy of a compressed air flow, where cryogenic temperatures are achieved within the flow behind the nozzle, when reaching a critical flow in order to maximize the energy gained. Compared to the energy of compressed air, the energy obtained thermoelectrically is negligible, but not zero. We are therefore primarily aiming to maximize the use of available energy sources. Behind the aperture separating regions with a pressure difference of several atmospheres, a supersonic flow with a large temperature drop develops. Based on the Seebeck effect, a thermocouple is placed in these low temperatures to create a thermoelectric voltage. This paper contains a mathematical-physical analysis for proper nozzle design, controlled gas expansion and ideal placement of a thermocouple within the flow for best utilization of the low temperature before a shockwave formation. If the gas flow passes through a perpendicular shockwave, the velocity drops sharply and the gas pressure rises, thereby increasing the temperature. In contrast, with a conical shockwave, such dramatic changes do not occur and the cooling effect is not impaired. This article also contains analyses for proper forming of the head shape of the thermocouple to avoid the formation of a detached shockwave, which causes temperature stagnation resulting in lower thermocouple cooling efficiency.

Efficient generation of spin polarization is very important for spintronics and quantum computation. In chiral materials without magnetic order nor spin-orbit coupling, we find a new spin selectivity effect—chiral phonon activated spin Seebeck (CPASS) effect. Starting with the nonequilibrium distribution of chiral phonons under a temperature gradient, the CPASS coefficients are computed based on the Boltzmann transport theory. With both the phonon-drag and band transport contributions, the spin accumulations generated by the CPASS effect exhibit quadratic dependence on the temperature gradient. The strength of the CPASS effect and the relative magnitude of both contributions are tunable by the chemical potential modulation. The CPASS effect, which gives a promising explanation on the traditional chiral-induced spin selectivity effect, provides opportunities for the exploration of advanced spintronic devices based on chiral materials even in the absence of any magnetic order and spin-orbit coupling.