Controlling heat by spin caloritronics*

Interaction between spin and heat is actively studied in the field of spin caloritronics from the viewpoints of both fundamental physics and applications. Early studies on spin caloritronics mainly focused on phenomena that generate a spin current from a heat current, such as the spin Seebeck effect, toward the development of versatile thermoelectric generators. In contrast, there are many heat-generation phenomena that use spin and charge currents as input, e.g., the spin Peltier effect, which is the reciprocal of the spin Seebeck effect; the anisotropic magneto-Peltier effect, in which the charge-to-heat current conversion efficiency depends on the angle between the charge current and magnetization in a ferromagnet; and the anomalous Ettingshausen effect, in which a heat current is generated in the direction perpendicular to both the applied charge current and magnetization. Recently, we successfully observed the thermal response from these phenomena by means of an active infrared emission microscopy called the lock-in thermography, and demonstrated thermal control functions that cannot be actualized without using spins [1-4]. In this talk, we review our recent experimental results by focusing particularly on the thermal imaging measurements of the spin-caloritronic phenomena.

[1] S. Daimon, R. Iguchi, T. Hioki, E. Saitoh, and K. Uchida, Nature Commun. 7, 13754 (2016).
[2] T. Seki, R. Iguchi, K. Takanashi, and K. Uchida, Appl. Phys. Lett. 112, 152403 (2018).
[3] K. Uchida, S. Daimon, R. Iguchi, and E. Saitoh, Nature 558, 95-99 (2018).
[4] K. Uchida et al., Scientific Reports 8, 16067 (2018).