Berlin 2024 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 48: Focus Session: Unconventional Thermoelectric Phenomena and Materials (joint session MA/TT)

TT 48.2: Invited Talk

Wednesday, March 20, 2024, 15:30–16:00, H 1058

Hybrid transverse magneto-thermoelectric cooling in artificially tilted multilayers — •Ken-ichi Uchida — National Institute for Materials Science, Tsukuba, Japan

In artificially tilted multilayers comprising two different conductors that are alternately and obliquely stacked, transverse thermoelectric conversion occurs, in which charge and heat currents are interconverted in the orthogonal direction. Although transverse thermoelectric conversion also occurs in homogeneous materials as intrinsic transport phenomena owing to the effects of magnetic fields, magnetization, and spins on conduction carriers, such magneto-thermoelectric effects have been investigated independently of thermoelectrics for artificially tilted multilayers. Here, we show that the synergy of these different principles improves the performance of transverse thermoelectric conversion. Using lock-in thermography techniques, we visualize transverse thermoelectric conversion processes in artificially tilted multilayers and experimentally clarify how nonuniform charge currents are converted into orthogonal heat currents. Through the measurements of temperature change under magnetic fields, we quantify the contributions of the magneto-thermoelectric effects in the artificially tilted multilayers and demonstrate magnetically enhanced hybrid transverse thermoelectric cooling. By replacing one of the conductors in the multilayer with permanent magnets, the same functionality is obtained even in the absence of magnetic fields, paving the way for the creation of thermoelectric permanent magnets. This study provides a new material design guideline for transverse thermoelectrics.

Keywords: transverse thermoelectrics; spin caloritronics; permanent magnet