Abstract
Conversion between spin and charge currents is essential in spintronics, since it enables spin-orbit-torque magnetization switching, spin-current-driven thermoelectric generation, and nano-scale thermal energy control. To realize efficient spin-charge conversion, a variety of mechanisms, including spin Hall effects, Rashba-Edelstein effects, and spin-momentum locking in topological insulators, have been investigated and more comprehensive material exploration is necessary. Here we demonstrate high-throughput screening of spin-charge conversion materials by means of the spin Peltier effect (SPE). This is enabled by combining recently-developed SPE-imaging techniques with combinatorial materials science; using a composition-spread alloy film formed on a magnetic insulator, we observe the SPE-induced temperature change due to the spin Hall effect and obtain a continuous mapping of its composition dependence from the single sample. The distribution of the SPE signals reflects local spin-charge conversion capability in the alloy owing to unique heat-generation nature of the SPE. This combinatorial approach will accelerate materials research towards high-performance spintronic devices.
Highlights
The spin-charge conversion is typically realized by the direct and inverse spin Hall effects[1,2,3,4] in a conductor with spin-orbit interaction
As a probe of the spin-charge current conversion, we focus on the spin Peltier effect (SPE)[16,17,18,19,20,21,22,23] driven by the direct spin Hall effect (DSHE) in a junction comprising a paramagnetic metal (PM) film and a ferrimagnetic insulator (FI)
To observe the SPE using the lock-in thermography (LIT) technique, we measured the spatial distribution of infrared radiation thermally emitted from the sample surface while applying a square-wave-modulated a.c. charge current with zero offset, amplitude of Jc = 2.7 mA, and frequency of f = 25 Hz to the Pt-W film and extracted the first
Summary
The spin-charge conversion is typically realized by the direct and inverse spin Hall effects[1,2,3,4] in a conductor with spin-orbit interaction. The inverse spin Hall effect (ISHE) refers to the conversion of a spin current into a transverse charge current, enabling electric detection of spin currents. We have developed a technique enabling systematic and high-throughput screening of spin-orbit materials by means of the LIT-based SPE measurements. By using the combinatorial material exploration together with the LIT technique, we have mapped the spatial distribution of the SPE signals in a composition-spread PM film formed on a single FI substrate. Since this method allows us to generate combinatorial libraries for the DSHE-driven SPE in a more efficient, reliable, and systematic way than conventional measurements, it will accelerate exploration of spin-orbit materials
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