Coupling heat with magnetization

Summary form only given. Spin caloritronics [1], an emerging branch of spintronics, studying the addition of thermal effects to the electrical and magnetic properties of nanostructures, has recently seen a rapid development . It has been predicted by Hatami et al . [2] that a heat current can exert a spin torque on the magnetization in a nanostructure, analogous to the well-known spin-transfer torque induced by an electrical current . Spin transfer torque is promising in applications in magnetic random access memory, known as STT-MRAM . [3] We provided the experimental evidence for the thermal spin-transfer torque effect in spin valves, showing the switching field change with heat current . [4] To observe spin caloritronic effect in ferromagnetic nanowires, we take advantage of two main detecting techniques, namely MTGV (magneto thermal galvanic voltage) and V2f (second harmonic voltage detection) .[5] In this presentation, I will introduce how we perform such measurements and a comparison of both, where similarity is observed and at the same time different aspects of physics behind are probed respectively . I will present measurements of the second harmonic voltage response of Co-CuCo pseudo-spinvalves deposited in the middle of Cu nanowires . These metallic nanowires are grown by electrodeposition in porous polycarbonate template . The diameter of the nanowires is about 50nm and the length is 6mm . In such samples, we exploit the quasi-1D nature of the nanostructures to generate a heat current by way of asymmetric Joule heating in the Co layers . Both the magnitude of the second harmonic response of the spin valve and the field value of the maximum response are found to be dependent on the heat current . Both effects show that the magnetization dynamics of the pseudospin-valves is influenced by the heat current . Thus, the data provide a quantitative estimate of the thermal spin torque exerted on the magnetization of the Co layers . Notably, Mojumder et al . [6] - ecently proposed a new type of MRAM based on thermal spin-transfer torque effect, thermagnonic MRAM as they name it . This opens new windows for applications of thermal spin transfer torque in low power-consumption spintronic devices .