Large Spin Accumulation with Long Spin Diffusion Length in Cu/MgO/Permalloy Lateral Spin Valves
We study the effect of interface resistance on the spin injection and detection efficiency in Cu/MgO/permalloy (Py) lateral spin valve devices. Insertion of the MgO layer enhances the spin accumulation by a factor of ten at 10 K: the maximum value is 10 m$\Omega$ at the interface resistance of $1.7\...
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| Published in | Applied physics express Vol. 4; no. 6; pp. 063002 - 063002-3 |
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| Main Authors | , , , |
| Format | Journal Article |
| Language | English |
| Published |
The Japan Society of Applied Physics
01.06.2011
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| Online Access | Get full text |
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| Summary: | We study the effect of interface resistance on the spin injection and detection efficiency in Cu/MgO/permalloy (Py) lateral spin valve devices. Insertion of the MgO layer enhances the spin accumulation by a factor of ten at 10 K: the maximum value is 10 m$\Omega$ at the interface resistance of $1.7\times 10^{-1}$ $\Omega$ (μm) 2 . The spin diffusion length of Cu reaches 1.3 μm at 10 K, which is twice larger than that of Ag/MgO/Py spin valves. As the interface resistance increases furthermore, the spin accumulation exponentially decreases. This can be explained by the large reduction of the spin polarization in the insulating layer. |
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| Bibliography: | Scanning electron microscope (SEM) image of the spin valve structure and electronic probing configuration. The widths of the Py and Cu wires are 100 and 200 nm, respectively, and the distance between the two Py wires is 700 nm. Typical NLSV signals with (broken line) and without (solid line) the MgO layer in between Cu and Py. The interface resistance of the Cu/MgO/Py contact is $3.5\times 10^{-1}$ $\Omega$ (μm) 2 , and the distance between the two Py wires is 500 nm for both samples. Distance dependence of the spin accumulation signal for the Ohmic devices measured at 10 K. From the fitting with eq. ( ), we can determine $P_{\text{F}} = 0.26$ and $\lambda_{\text{N}} = 1.3$ μm. Spin accumulation signals as a function of the MgO interface resistance measured at (a) 10 K and (b) room temperature. The separation distance $d$ between the two Py wires is changed from 300 to 700 nm. The solid curves are the best fits of eq. ( ) with the same parameters as shown in Fig. . The broken curves are the best fits of eq. ( ) combined with eq. ( ). |
| ISSN: | 1882-0778 1882-0786 |
| DOI: | 10.1143/APEX.4.063002 |