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Transverse thermoelectric generation converts temperature gradient in one direction into an electric field perpendicular to that direction and is expected to be a promising alternative in creating simple‐structured thermoelectric modules that can avoid the challenging problems facing traditional Seebeck‐effect‐based modules. Recently, large transverse thermopower has been observed in closed circuits consisting of magnetic and thermoelectric materials, called the Seebeck‐driven transverse magneto‐thermoelectric generation (STTG). However, the closed‐circuit structure complicates its broad applications. Here, STTG is realized in the simplest way to combine magnetic and thermoelectric materials, namely, by stacking a magnetic layer and a thermoelectric layer together to form a bilayer. The transverse thermopower is predicted to vary with changing layer thicknesses and peaks at a much larger value under an optimal thickness ratio. This behavior is verified in the experiment, through a series of samples prepared by depositing Fe–Ga alloy thin films of various thicknesses onto n‐type Si substrates. The measured transverse thermopower reaches 15.2 ± 0.4 µV K−1, which is a fivefold increase from that of Fe–Ga alloy and much larger than the current room temperature record observed in Weyl semimetal Co2MnGa. The findings highlight the potential of combining magnetic and thermoelectric materials for transverse thermoelectric applications. [ABSTRACT FROM AUTHOR]

We phenomenologically calculate the performance of the recently observed Seebeck-driven transverse thermoelectric generation (STTG) for various systems in terms of the thermopower, power factor, and figure of merit to demonstrate the usefulness of STTG. The STTG system consists of a closed circuit comprising thermoelectric and magnetic materials which exhibit the Seebeck and anomalous Hall effects, respectively. When a temperature gradient is applied to the hybrid system, the Seebeck effect in the thermoelectric material layer generates a longitudinal charge current in the closed circuit, and the charge current subsequently drives the anomalous Hall effect in the magnetic material layer. The anomalous Hall voltage driven by the Seebeck effect has a similar symmetry to the transverse thermoelectric conversion based on the anomalous Nernst effect. We find that the thermoelectric properties of STTG can be much better than those of the anomalous Nernst effect by increasing the Seebeck coefficient and anomalous Hall angle of the thermoelectric and magnetic materials, respectively, as well as by optimizing their dimensions. We also formulate the electronic cooling performance in the STTG system, thereby confirming the reciprocal relation for the hybrid transverse thermoelectric conversion. [ABSTRACT FROM AUTHOR]

An unconventional approach to enhance the transverse thermopower by combining magnetic and thermoelectric materials, namely the Seebeck-driven transverse thermoelectric generation (STTG), has been proposed and demonstrated recently. Here, we improve on the previously used sample structure and achieve large transverse thermopower over 40 ÎĽ V Kâˆ'1 due to STTG in on-chip devices. We deposited polycrystalline Feâ€"Ga alloy films directly on n-type Si substrates, where Feâ€"Ga and Si serve as the magnetic and thermoelectric materials, respectively. Using microfabrication, contact holes were created through the SiO x layer at the top of Si to electrically connect the Feâ€"Ga film with the Si substrate. These thin devices with simple structure clearly exhibited enhancement of transverse thermopower due to STTG, and the obtained values agreed well with the estimation over a wide range of the size ratio between the Feâ€"Ga film and the Si substrate. [ABSTRACT FROM AUTHOR]

The negative sign of the anomalous Nernst thermopower ( S ANE ) observed in Mn-Ga ordered alloys is an attractive property for thermoelectric applications exploiting the anomalous Nernst effect (ANE); however, its origin has not been clarified. In this study, to gain insight into the negative S ANE , we prepared epitaxial thin films of MnxGa100−x with x ranging from 56.2 to 71.7 and systematically investigated the structural, magnetic, and transport properties, including the anomalous Hall effect (AHE) and the ANE. The measured S ANE is negative for all samples and shows close to one order of magnitude difference among different compositions. Together with the measured transport properties, we were able to separate the two different contributions of the ANE, i.e., one originating from the transverse thermoelectric coefficient (αxy) and the other one originating from the AHE acting on the longitudinal carrier flow induced by the Seebeck effect. Both contributions are found to be negative for all samples, while the experimentally obtained negative αxy exhibits a monotonic increase toward zero with increasing x, which is consistent with the tendency indicated by first-principle calculations. Our results show that the large difference in the negative S ANE is mostly attributed to αxy, and thus shed light on further enhancement of the ANE in Mn-based ordered alloys. [ABSTRACT FROM AUTHOR]