Spin-Hall magnetoresistance in platinum on yttrium iron garnet Vlietstra, N.; Shan, J.; Castel, V.; van Wees, B. J.; Ben Youssef, J. Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. The occurrence of spin-Hall magnetoresistance (SMR) in platinum (Pt) on top of yttrium iron garnet (YIG) has been investigated, for both in-plane and out-of-plane applied magnetic fields and for different Pt thicknesses [3, 4, 8, and 35 nm]. Our experiments show that the SMR signal directly depends on the in-plane and out-of-plane magnetization directions of the YIG. This confirms the theoretical description, where the SMR occurs due to the interplay of the spin-orbit interaction in the Pt and the spin-mixing conductance at the YIG/Pt interface. Additionally, the sensitivity of the SMR and spin pumping signals on the YIG/Pt interface conditions is shown by comparing two different deposition techniques (e-beam evaporation and dc sputtering).

The effective field torque of an yttrium-iron-garnet (YIG) film on the spin accumulation in an attached platinum (Pt) film is measured by the spin-Hall magnetoresistance (SMR). As a result, the magnetization direction of a ferromagnetic insulating layer can be measured electrically. Experimental transverse and longitudinal resistances are well described by the theoretical model of SMR in terms of the direct and inverse spin-Hall effect, for different Pt thicknesses [3, 4, 8, and 35 nm]. Adopting a spin-Hall angle of Pt h SH ¼ 0:08, we obtain the spin diffusion length of Pt (k ¼ 1:1 6 0:3 nm) as well as the real (G r ¼ ð7 6 3Þ Â 10 14 X À1 m À2 ) and imaginary part (G i ¼ ð5 6 3Þ Â 10 13 X À1 m À2 ) of the spin-mixing conductance and their ratio (G r =G i ¼ 16 6 4). In spintronics, interfaces between magnets and normal metals are important for the creation and detection of spin currents, which is governed by the difference of the electric conductance for spin up and spin down electrons.1-3 Another important interaction between the electron spins in the magnetic layer and those in the normal metal, that are polarized perpendicular to the magnetization direction, is governed by the spin-mixing conductance G "# , 4 which is composed of a real part and an imaginary part (G "# ¼ G r þ iG i ). G r is associated with the "in-plane" or "Slonczewski" torque along m Âl Âm, 5-7 wherem is the direction of the magnetization of the ferromagnetic layer andl is the polarization of the spin accumulation at the interface. G i describes an exchange magnetic field that causes precession of the spin accumulation aroundm. This "effective-field" torque associated with G i points towardsl Âm.While several experiments succeeded in measuring G r , 3,4,7-10 G i is difficult to determine experimentally, mainly because it is usually an order of magnitude smaller than G r . 4The recently discovered spin-Hall magnetoresistance (SMR) 11-14 offers the unique possibility to measure G i for an interface of a normal metal and a magnetic insulator by exposing it to out-of-plane magnetic fields. Althammer et al.15 carried out a quantitative study of the SMR of Yttrium Iron Garnet (YIG)/Platinum (Pt) bilayers. They obtained an estimate of G i ¼ 1:1 Â 10 13 X À1 m À2 by extrapolating the high field Hall resistances to zero magnetic field. 16In this paper, we report experiments in which the contribution of G r and G i can be controlled by changing the magnetization direction of the YIG layer by an external magnetic field. Thereby either G r or G i can be made to dominate the SMR. By fitting the experimental data by the theoretical model for the SMR, 11 the magnitude of G r , G i , and the spin diffusion length k in Pt are determined.For SMR measurements, Pt Hall bars with thicknesses of 3, 4, 8, and 35 nm were deposited on YIG by dc sputtering.12 Simultaneously, a reference sample was fabricated on a Si/SiO 2 substrate. The length and width of the Hall bars are 800 lm and 100 lm, respectively. The YIG has a thickness of 200 nm and is grown by liquid ...

We show the first experimental observation of the platinum (Pt) thickness dependence in a hybrid YIG/Pt system of the inverse spin-Hall effect from spin pumping, over a large frequency range and for different rf powers. From the measurement of the dc voltage (∆V) at the resonant condition and the resistance (R) of the Pt layer, a strong enhancement of the ratio ∆V/R has been observed, which is not in agreement with previous studies on the NiFe/Pt system. The origin of this behaviour is still unclear and cannot be explained by the spin transport model that we have used.

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Frequency and power dependence of spin-current emission by spin pumping in a thin-film YIG/Pt system Castel, V.; Vlietstra, N.; van Wees, B. J.; Ben Youssef, J. Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. This paper presents the frequency dependence of the spin-current emission by spin pumping in a hybrid ferrimagnetic insulator/normal metal system. The system is based on a ferrimagnetic insulating thin film of yttrium iron garnet (YIG, 200 nm) grown by liquid-phase epitaxy coupled with a normal metal with a strong spin-orbit coupling (Pt, 15 nm). The YIG layer presents an isotropic behavior of the magnetization in the plane, a small linewidth, and a roughness lower than 0.4 nm. Here we discuss how the voltage signal from the spin-current detector depends on the frequency (0.6-7 GHz), the microwave power, P in (1-70 mW), and the in-plane static magnetic field. A strong enhancement of the spin-current emission is observed at low frequencies, showing the appearance of nonlinear phenomena.