Charge-current angle and frequency dependences of the spin Peltier effect induced by the spin Hall effect

The spin Peltier effect (SPE) induced by the spin Hall effect has been investigated in Pt/yttrium-iron-garnet (YIG) junctions by the lock-in thermography technique. First, we propose and demonstrate a new method enabling systematic measurements of the charge-current angle dependence of spin-caloritronic and thermoelectric phenomena, confirming the symmetry of the SPE. Then, to investigate the temporal response of the SPE, we measured the charge-current frequency dependence of the spin-current-induced temperature modulation in a wide frequency range. The SPE signals are found to be almost independent of the frequency up to 100 Hz although the Joule-heating signals in the Pt layer are strongly dependent on the frequency, indicating that the spin-current-induced temperature modulation reaches the steady state in a much shorter time than the conventional heating effects. The experimental methods and results reported here will be useful for clarifying mechanisms and behaviors of spin-caloritronic and thermoelectric phenomena. (author)