Spin Seebeck effect and Anomalous Nernst effect in CFA/W bilayer with uniaxial and cubic magnetocrystalline anisotropies

Full text: New and more efficient ways to make use the internal energy converted into heat in electronic devices are of crucial importance for a sustainable future. In the field of spintronics, the spin caloritronics is an active and exciting area of research with potential to the development of energy-efficient technologies, covering the impacts of a temperature gradient on the production of spin and charge currents in materials. In magnetic materials, the thermoelectric voltage, defined as the direct conversion of the temperature gradient to electrical voltage, is primarily associated to two phenomena, the spin Seebeck effect (SSE) and the anomalous Nernst effect (ANE). In this work, we investigated both, SSE and ANE, in Co₂FeAl/W grown onto GaAs substrate. The samples were prepared by magnetron sputtering with the substrate under to distinct temperature conditions during deposition, from 300 up to 773 K. Here, the bilayers were deposited onto oriented GaAs(100) substrates in order to induce magnetocrystalline anisotropy, thus allowing us the obtainment of systems with uniaxial and cubic contributions. The samples were characterized from the structural and magnetic point of views. Specifically, the structural characterization was performed by X-ray diffractometry, while the quasi-static magnetic behavior was obtained through magnetization curves measured using a vibrating sample magnetometer. Thermoelectric response was explored via Longitudinal Spin Seebeck Effect (LSSE). In this configuration, the temperature gradient is normal to the plane of the film, and the external magnetic field lies in the plane. Then, the thermoelectric voltage is acquired with electrical contacts fixed in the film plane. The thermoelectric response in the samples is a result of the interplay between the uniaxial and cubic contributions of the magnetocrystalline anisotropy. The results place Co₂FeAl/W grown onto GaAs substrate as a promising candidate for active elements in spintronic devices. (author)