Abstract

This article presents a meticulous analysis of the rapidly evolving field of spin-based electronics, centering on the critical role of Spin Caloritronics in novel material systems. The key aim is to integrate significant results from a broad range of recent investigations related to Heavy-Metal/Ferromagnet interfaces. We explore the underlying physics, experimental progress, and potential applications emphasized in the existing academic discourse. This review aims to create a informative guide for Ignou MBA Project scientists involved in this intriguing area of nanotechnology.

1. Introduction

The quest for energy-efficient computing components has driven significant study into spin-based electronics, which utilizes the electron's spin attribute in as well as its charge. Early spintronic devices, such as Giant Magnetoresistance (GMR) sensors, rely on spin-polarized electron flow and external fields for switching. However, the need for more efficient, miniaturizable, and energy-frugal performance has prompted the investigation of alternative control methods, such as Spin Caloritronics. These mechanisms enable the direct switching of magnetic moments via current pulses in specially engineered multilayers, establishing them as particularly compelling for applications in non-volatile memory chips.

2. Fundamental Principles and Mechanisms

The underlying basis of Spin Caloritronics stems from the intricate interplay between magnetism, electronic structure, and charges in solid-state materials. In the context of Spin-Orbit Torque, the key driver is the Rashba-Edelstein Effect (REE). The REE converts a flow of electrons in a heavy metal (e.g., Pt) into a transverse spin current, which subsequently applies a torque on the neighboring ferromagnetic layer, possibly switching its polarization. Likewise, VCMA operates through the alteration of interface properties by means of the use of an electric field at an junction, thus reducing the energy barrier required for magnetization switching. On the other hand, Spin Caloritronics deals with the interconversion between heat currents and thermal gradients, presenting pathways for thermal energy conversion and new sensing schemes.

3. Review of Key Material Systems

The performance of SOT switching is extremely contingent on the choice of materials and the quality of their interfaces. This review examines three primary material systems:

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• Heavy-Metal/Ferromagnet Bilayers: This is the archetypal system for investigating SOT. Elements like Pt serve as efficient spin Hall effect generators, while CoFeB serves as the switchable layer. Studies has centered on tuning parameters such as interface transparency to improve the switching efficiency.
  
• Complex Oxide Interfaces: These heterostructures integrate magnetic and polar properties in a composite material. The primary interest for VCMA is the significant coupling between electric polarization and magnetic anisotropy, which can lead to