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

Abstract

Anisotropic magnetoresistance (AMR) ratio and anomalous Hall conductivity (AHC) in PdPt/Y 3 Fe 5 O 12 (YIG) system are tuned significantly by spin orbital coupling strength ξ through varying the Pt concentration. For both Pt/YIG and Pd/YIG, the maximal AMR ratio is located at temperatures for the maximal susceptibility of paramagnetic Pt and Pd metals. The AHC and ordinary Hall effect both change the sign with temperature for Pt-rich system and vice versa for Pd-rich system. The present results ambiguously evidence the spin polarization of Pt and Pd atoms in contact with YIG layers. The global curvature near the Fermi surface is suggested to change with the Pt concentration and temperature. PACS numbers: 72.25.Mk, 72.25.Ba, 75.70.-i * Correspondence author. Electronic mail: shiming@tongji.edu.cn 1 Generation, manipulation, and detection of pure spin current are popular topic in the community of spintronics because of its prominent advantage of negligible Joule heat in spintronic devices [1][2][3][4][5] . Pure spin current can be generated by spin Hall effect, spin Seebeck effect (SSE), and etc. By spin Hall effect, the pure spin current can be achieved in semiconductors due to strong spin orbital coupling (SOC). In the SSE approach, the spin current is produced in ferromagnetic materials with a temperature gradient and injected into another nonmagnetic layer through the interface. In general, the pure spin current cannot be probed by conventional electric approach. Instead, it is detected by inverse spin Hall effect 6,7 .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. 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. The AMR ratio of Pt/YIG system exhibits an angular dependence different from the conventional AMR in magnetic films, and it changes nonmonotonically with the Pt layer thickness. Although these phenomena were attributed to spin Hall magnetoresistance (SMR) 14,15 instead of the conventional AMR, the nonmonotonic variation of the AMR with T cannot be understood in the SMR model 13 . Moreover, the ferromagnetic ordering in Pt layers was proved by the anomalous Hall effect (AHE) in Pt/YIG system 9 . In particular, the mechanism of the observed sign change of the AHE with T is still unclear. Very rece...

Interfacial contributions to anomalous Hall effect in perpendicular magnetic anisotropic [Co2MnSi/Pd]3 multilayer

“…For the as-deposited multilayer, ρ AH increases with the increase of measuring temperature. It is noteworthy that ρ AH decreases nonlinearly with increasing measuring temperature for all annealed multilayers, which also differs from reports for Co 2 MnSi monolayer and other multilayer systems such as CoFeB/Pt and Fe/Au [22,24,31], while it is similar to the tendency of Pd/YIG film [46]. For the Pd/YIG system, it is suggested that the magnetic proximity plays an important role in contributing to AHE, which could lead to the decreased ρ AH with increasing measuring temperature [46].…”

Exploring interfacial exchange coupling and sublattice effect in heavy metal/ferrimagnetic insulator heterostructures using Hall measurements, x-ray magnetic circular dichroism, and neutron reflectometry

“…Smaller saturation magnetization leads to weaker exchange interaction and thus lower Ton,MPE. Negative [6,28] Negative (this work) Table I…”

“…With the information from the AHE, we can extract the exchange coupling configuration in arbitrary HM/magnetic insulator (MI) bilayers. For instance, Zhou et al[6] and Amamou et al[29] observed the AHE signs due to MPE are negative and positive for the Pd/YIG and Pt/CoFe2O4 (CoFe2O4 is a MI), respectively, so that we can predict parallel exchange coupling for both Pd/YIG and Pt/CoFe2O4 by usingTable I. We also summarize results of the exchange coupling configurations in HM/magnet bilayers inTable II[6,26,27,[29][30][31],…”

Antiferromagnet-controlled spin current transport inSrMnO3/Pthybrids

“…The spin Hall magnetoresistance (SMR) and the spin Seebeck effect are two interesting observations when Pt is attached to a ferromagnetic insulator Y 3 Fe 5 O 12 (YIG), both of which are related to a pure spin current flowing along the direction normal to the YIG/Pt interface [5][6][7][8][9]. Unfortunately, the possible existence of the magnetic proximity effect (MPE) at the YIG/Pt interface complicates the detection of the SMR signals [10][11][12][13][14][15][16]. Similarly, the MPE-induced FM ordering in the Pt film associated with the anomalous Nernst effect becomes an obstacle for the quantitative characterizations of the spin Seebeck effect, due to an induced spin polarized current parallel with the spin current [16][17][18][19].…”