Longitudinal Spin Seebeck Effect Free from the Proximity Nernst Effect

Abstract

This Letter provides evidence for intrinsic longitudinal spin Seebeck effects (LSSEs) that are free from the anomalous Nernst effect (ANE) caused by an extrinsic proximity effect. We report the observation of LSSEs in Au/Y(3)Fe(5)O(12) (YIG) and Pt/Cu/YIG systems, showing that the LSSE appears even when the mechanism of the proximity ANE is clearly removed. In the conventional Pt/YIG structure, furthermore, we separate the LSSE from the ANE by comparing the voltages in different magnetization and temperature-gradient configurations; the ANE contamination was found to be negligibly small even in the Pt/YIG structure.

Thermally driven spin and charge currents in thin NiFe2O4/Pt films

“…For a quantitative comparison of the ratio of the saturation voltage signal V sat and the temperature difference ∆T , Kikkawa et al introduce the ratioṼ sat /∆T including geometric factors of the sample 24 . This coefficient is given by the formulaṼ sat = V sat L z /L y , where L z is the sample thickness in the direction of the temperature gradient and L y is the length of the sample in the y-direction.…”

“…Recently, a study of the ANE in YIG/Pt compares the magnitudes of the ANE and LSSE voltage signals by exchanging the temperature gradient ∇T and the external magnetic field H, but in different configurations 24 . This study shows that the contribution of the ANE due to proximity effect is less than 5% of the voltage signal in the LSSE configuration.…”

Tuning magnetotransport in PdPt/Y3Fe5O12: Effects of magnetic proximity and spin-orbit coupling

“…Many attempts have been made to study the MPE in Pt/YIG system. Since the atomic magnetic moment of Pt is too small to be measured by magnetometry, anisotropic magnetoresistance (AMR) and anomalous Hall effect (AHE) have been investigated intensively as a function of the Pt layer thickness and sampling temperature (T ) [10][11][12][13][14][15][16] . Up to date, however, magnetotransport results are controversial.…”

“…With strong SOC in Pt layers and long spin diffusion length in Y 3 Fe 5 O 12 (YIG) insulator layers, the Pt/YIG systems are particularly suitable for design and fabrication of spintronic devices [8][9][10][11][12][13][14][15][16][17] . In studies of the SSE phenomena of Pt/YIG system, the SEE and the anomalous Nernst effect were argued to be entangled 9 , where the latter comes from the spin polarization due to the magnetic proximity effect (MPE) of the nearly ferromagnetic Pt layers.…”

Continuous control of spin polarization using a magnetic field

“…Spintronic effects, such as giant magnetoresistance (GMR), 1,2 tunnel magnetoresistance (TMR), 3 spin-transfer torque (STT), 4,5 and pure spin currents in spin Seebeck effect (SSE), 6,7 are intimately related to spin of the conduction electrons. In many materials, the number of spin-up and spin-down electrons is not necessarily the same, and is measured by the spin polarization (P), which is defined as the imbalance of spin-up and spin-down electrons at the Fermi level, normalized by the total number of electrons, [8][9][10][11][12][13][14][15] P N " E F ð ÞÀN # ðE F Þ N " E F ð ÞþN # ðE F Þ .…”