Spin Seebeck effect and spin Hall magnetoresistance in the Pt/Y ₃ Fe ₅ O ₁₂ heterostructure under laser-heating

Abstract

In the previous study of longitudinal spin Seebeck effect (LSSE), the thermal gradient was often generated by inserting the sample between the cool bath and the hot bath. For practical use, this method is too cumbersome to be easily integrated into modern electrical circuits. Since the laser can be easily focused into a small region, it will be more convenient and friendly to the integrated circuit. In this paper, we systematically investigate the LSSE and spin Hall magnetoresistance (SMR) of the Pt/Y 3 Fe 5 O 12 heterostructure under focused laser-heating. We find that the extremely large voltage of inverse spin Hall effect (V ISHE ) can be obtained by reducing the diameter of laser or increasing the number of light spots. Meanwhile, even under the illumination of the ultraviolet light which will excite the electron from the valence band to the conduction band in yttrium iron garnet (YIG), the magnitude of SMR is nearly constant. It indicates that the spin transport behavior of the adjacent Pt is independent of the electron configuration of YIG. The laser-heating method to generate LSSE will be very promising for modern integrated electronic circuits and will promote the application of spin caloritronics in practice.

Origin of the light-induced spin currents in heavy metal/magnetic insulator bilayers

“…Note that light-induced spin current is also considered as a light-thermally excited spin current (i.e., SSE), and the smaller-spot laser with higher energy (i.e., high light intensity) is used, and the thickness of samples is generally in the range of micrometer 13 , 14 , 25 . Consequently, a large Δ z T and reversal of the Δ z T sign with a reversed illumination direction led to the flipped sign of V ISHE .…”

Magnetization reorientation induced by spin–orbit torque in YIG/Pt bilayers*

“…This setup has been used because the transversal resistivity V y presented a low background signal and thus gave a high signal-to-noise ratio. [23,34] The angle between the external magnetic field and J e is defined as β , and we define β as the angle between the magnetic moment (𝑀 ) and J e . The value of SMR is sensitively dependent on the direction between 𝑀 and J e .…”

Field-induced Néel vector bi-reorientation of a ferrimagnetic insulator in the vicinity of compensation temperature*

“…However, at present, it is generally believed that the Néel vector of the compensated ferrimagnets undergoes an SF transition, and then all the sub-lattice moments turn toward H with a further increase in H. [18,19,21] Most of the magnetic measurement techniques are not able to measure the Néel vector of the compensated ferrimagnets because of the near-zero magnetization. The spin Hall magnetoresistance (SMR) [22,23] was previously demonstrated to act as a convenient tool for measuring the orientation of the Néel vector of an AFM insulator. [24][25][26] In this study, we successfully used SMR to assess the magnetic order transition induced by the temperature (T ) and H around T M of Gd 3 Fe 5 O 12 (GdIG).…”