Gallium Iron room temperature Magnetoelectric Oxides

磁电(ME)材料在其磁性和电性之间呈现耦合，允许通过电场来控制材料的磁化。这为具有高耐久性、低存取时间和低功耗的新型非易失性存储器开辟了前景：磁电存储器(MERAM)。不幸的是，呈现ME联轴器的材料很少。那些在室温下呈现这种效应并具有非零磁化强度的材料，对于真正的应用开发来说是必不可少的。我们建议从一种有前途但仍然未知的材料的磁电角度来研究这种可能性，特别是在薄膜中：Ga2-xFexO3(GFO)。这种材料是热释电的、亚铁磁性的，并且是单相材料中最高的ME耦合之一。这是观察到的第一种同时出现强ME耦合和由此产生的磁化的材料。当x=1.4时，其居里温度高于室温(370K)。然而，它的电学和ME特性的来源仍然不清楚。直到最近，还不能用这种材料制造出足够高结晶质量的薄膜。这实际上消除了它在电子设备中的潜在应用。该项目提议利用其中一个合作伙伴最近获得的能力来沉积高质量的GFO薄膜。它的目标是对GFO磁电进行完整的理论和实验研究。理论部分将包括第一原理计算，目的是确定GFO中ME效应的来源，以期找到增加ME效应的方法。在理论部分的指导下，考虑了GFO结构的不同掺杂。理论部分的一致性将在以后通过将其预测与纯和掺杂的GFO薄膜的ME效应实验表征进行比较来评估。

Magnetoelectric (ME) materials, presenting a coupling between their magnetic and electric properties, allow the control of the magnetization of a material through an electric field. This opens perspectives towards a new type of non volatile memory with high endurance, low access time and low power consumption: magnetoelectric memories (MERAMs). Unfortunately, materials presenting a ME coupling are scarce. Those presenting this effect at room temperature and having a non zero magnetization, essential for the real development of the applications, are even scarcer.We propose to study the possibilities in terms of magnetoelectricity of a promising but still rather unknown material, especially in thin films: Ga2-xFexO3 (GFO). This material is pyroelectric, ferrimagnetic, and has one of the highest ME couplings observed for a single-phased material. It’s the first material observed to simultaneously present a strong ME coupling and a resulting magnetization. Its Curie temperature is above room temperature (370 K) for x=1.4. The origin of its electric and ME properties is however still unclear. Until recently, no sufficiently high crystalline quality thin films of this material could be made. This de facto annihilated its potential applications in electronic devices.This project proposes to take advantage of the ability recently acquired by one of the partners to deposit high quality GFO thin films. Its goal is to perform a complete theoretical and experimental study of GFO magnetoelectricity. The theoretical part will consist in first principles calculations aiming at determining the origin of the ME effect in GFO, with a view to find ways to increase it. Different dopings of the GFO structure will be considered, guided by the theoretical part. Consistency of the theoretical part will be evaluated a posteriori through comparison of its predictions with the ME effect experimental characterization of pure and doped GFO thin films.