Bolometric Properties of a Spin-Torque Diode Based on a Magnetic Tunnel Junction

G D Demin,A F Popkov,K A Zvezdin

doi:10.1155/2019/5109765

Abstract

Spin caloritronics opens up a wide range of potential applications, one of which can be the thermoelectric rectification of a microwave signal by spin-diode structures. The bolometric properties of a spin-torque diode based on a magnetic tunnel junction (MTJ) in the presence of a thermal gradient through a tunnel junction are discussed. Theoretical estimates of the static and dynamic components of the microwave sensitivity of the spin-torque diode, related to thermoelectric tunnel magneto-Seebeck effect and the thermal transfer of spin angular momentum in the MTJ under nonuniform heating, are presented. Despite the fact that the thermal contribution to the microwave sensitivity of the spin-torque diode is found to be relatively small in relation to the rectification effect related to the modulation of the MTJ resistance by a microwave spin-polarized current, nevertheless, the considered bolometric effect can be successfully utilized in some real-world microwave applications.

Highlights

The magneto-Seebeck effect and the thermal initiating spintransfer torques in magnetic tunnel junction (MTJ) are an important part of spincaloritronic studies [1,2,3,4,5,6,7] and are of a high significance for development of nonvolatile memory and temperaturesensitive devices [8,9,10]
The analysis performed shows that microwave sensitivity of the spin-torque diode to the microwave irradiation along with the electric contribution contains the thermal one
The latter in turn, in addition to the ordinary contribution due to the static Seebeck effect caused by the constant temperature drop, contains a dynamic contribution originating from the thermal transfer of the spin angular momentum modulated at the frequency of microwave irradiation

Summary

Introduction

The magneto-Seebeck effect and the thermal initiating spintransfer torques in MTJ are an important part of spincaloritronic studies [1,2,3,4,5,6,7] and are of a high significance for development of nonvolatile memory and temperaturesensitive devices [8,9,10]. In addition to the constant component VDTCH0 of the voltage drop across the tunnel layer due to the presence of the static Seebeck effect, the thermal heating of the MTJ under a.c. current results in a frequency-dependent constant voltage ΔVDC(ω) This voltage is associated with the rectification effect of the signal due to modulation of the magnetoresistance induced by the spintorque components related to the time-varying part of the temperature drop ΔTB1(ω) cos ωt. To determine the dynamic response of the magnetic system of an MTJ to a time-varying part of the frequency-dependent temperature drop ΔTB(ω), we linearized the Landau-Lifshitz-Gilbert equation describing the magnetization dynamics of a free ferromagnetic layer near the equilibrium position m ≈ m0 = ey, taking into account both in-plane and perpendicular (or field-like) components of two spin-transfer torques (thermal and current-induced) created by heat and by external electric current, correspondingly: ṁ.

Microwave Sensitivity

Conclusions