WTe2单晶样品的极大磁阻效应随掺杂的演变及其机理研究

Materials with large magnetoresistance have broad and significant application in modern products, such as magnetic sensors, magnetic memories, hard drives, and etc. Recently people discovered extremely large magnetoresistance (XMR) in several nonmagnetic materials. Understanding the mechanism of XMR would facilitate its application. In this project, we will focus on the mechanism of XMR in the non-magnetic layered transition-metal dichalcogenide WTe2. Two possible explanations for XMR are nearly perfect balanced electron-hole population, that is certain Fermi surface topology, and strong spin-orbital coupling, respectively. We will synthesize a series of doped WTe2 single crystals with high quality, which exhibit different Fermi surface topologies and spin-orbital couplings. By measuring their transport properties, magnetoresistances and quantum oscillations will be obtained, and the latter could be used to calculate the Fermi surface topology. Besides, we could reveal their Fermi surface topologies directly by performing angle-resolved photoemission spectroscopy measurements on them. Moreover, combining the first-principle calculation, we could unveil the relationship between magnetoresistance and Fermi surface topology or spin-orbital coupling, respectively. Our study would facilitate the exploration of new materials with XMR and their possible application in the room temperature.

磁阻效应在现代科技产品中有着重要而广泛的应用，包括磁传感器、磁卡和硬盘等。近年来人们在非磁材料中发现了极大磁阻效应，对于其机理的理解是拓展相关材料实际应用价值的关键。本项目将着重研究二硫族化合物WTe2中出现极大磁阻效应的机理，其目前两个可能的解释分别是近乎完美平衡的电子空穴载流子（即费米面拓扑结构）和很强的自旋轨道耦合作用。本项目将合成一系列高质量的WTe2掺杂单晶样品来调节其费米面拓扑结构和自旋轨道耦合作用，利用输运测量给出其磁阻效应和量子振荡并计算出其费米面拓扑结构，利用角分辨光电子能谱技术直接给出其费米面拓扑结构，同时结合第一性原理计算，从而分别得到极大磁阻效应和费米面拓扑结构及自旋轨道耦合之间一一对应的关系，并帮助解释WTe2中出现极大磁阻效应的机理。本项目将为进一步探索新型具有极大磁阻效应的材料和研究极大磁阻效应在室温下实现的可能性铺平道路。

磁阻效应在现代科技产品中有着重要而广泛的应用，包括磁传感器、磁卡和硬盘等。近年来人们在非磁材料中发现了极大磁阻效应，对于其机理的理解是拓展相关材料实际应用价值的关键。本项目将着重研究二硫族化合物WTe2中出现极大磁阻效应的机理，其目前两个可能的解释分别是近乎完美平衡的电子空穴载流子（即费米面拓扑结构）和很强的自旋轨道耦合作用。目前的研究表明传统的气相输运法和助溶剂法难以生长出掺杂的WTe2单晶样品，需要通过PLD或者MBE等薄膜生长设备来合成其掺杂样品，利用原位的ARPES测量其电子结构，利用PPMS研究其磁阻效应，从而分别得到极大磁阻效应和费米面拓扑结构及自旋轨道耦合之间一一对应的关系，并帮助解释WTe2中出现极大磁阻效应的机理。本项目将为进一步探索新型具有极大磁阻效应的材料和研究极大磁阻效应在室温下实现的可能性铺平道路。