Transient response of the spin Peltier effect revealed by lock-in thermoreflectance measurements

Abstract

a) E-mail: IGUCHI.Ryo@nims.go.jp [Abstract] Transient response of the spin Peltier effect (SPE) in a Pt/yttrium iron garnet junction system has been investigated by means of a lock-in thermoreflectance method. We applied an alternating charge current to the Pt layer to drive SPE through the spin Hall effect, and measured the AC response of the resultant SPE-induced temperature modulation at frequencies ranging from 10 Hz to 1 MHz. We found that the SPE-induced temperature modulation decreases with increasing the frequency when the frequency is >1 kHz. This is a characteristic feature of SPE revealed by the high frequency measurements based on the lock-in thermoreflectance, while previous low frequency measurements showed that the SPE signal is independent of the frequency. We attribute the decrease of the temperature modulation to the length scale of the SPE-induced heat current; by comparing the experimental results with one-dimensional heat conduction calculations, the length scale of SPE is estimated to be 0.94 μm.

Spin Peltier effect and its length scale in Pt/YIG system at high temperatures

“…In fact, the characteristic length for SPE in Fig. 4(b) is comparable to that estimated in the previous SPE experiments 24,26,27) but smaller than that estimated in the previous SSE experiments. 15,[29][30][31][32][33] This situation indicates that the Onsager reciprocal relation between SPE and SSE is not simple and its magnon frequency dependence should be taken into account.…”

“…The l SPE value near room temperature (314 K) is estimated to be 0.9 μm, which is comparable to the values obtained in the previous studies on SPE. 24,26,27) We found that l SPE remains almost constant as the temperature increases. Next, we compare the T dependence of the SPE signal with that of the SSE voltage.…”

Thickness dependence of spin Peltier effect visualized by thermal imaging technique

“…The Onsager reciprocal of SSE is the spin Peltier effect (SPE). [4][5][6][7][8][9][10][11] A typical system used for studying SPE and SSE is paramagnetic metal Pt/ferrimagnetic insulator yttrium iron garnet (YIG) junction systems, [3][4][5]7,[12][13][14][15] where the spin and heat currents are carried by electron spins in Pt and magnons in YIG. [16][17][18][19] SPE and SSE are characterized by their length scale including the magnon-spin diffusion length l m and the magnon-phonon thermalization length l mp in YIG.…”

Large spin-Hall effect in non-equilibrium binary copper alloys beyond the solubility limit

“…The SPE-induced temperature modulation appears only within the wires and the thermal diffusion is suppressed. This is attributable to the dipolar heat sources placed near the sample surface by the SPE 35,39,43 . Figure 2g shows A SPE as a function of y D in the left Cu-Ir wire with t = 30 nm.…”