Su Haotian, Kwon Heungdong, Xue Fen, Sato Noriyuki, Bhat Usha, Tsai Wilman, Bosman Michel, Asheghi Mehdi, Goodson Kenneth E, Pop Eric, Wang Shan X
Department of Electrical Engineering, Stanford University, Stanford, California 94305, United States.
Department of Mechanical Engineering, Stanford University, Stanford, California 94305, United States.
Nano Lett. 2024 Nov 20;24(46):14567-14573. doi: 10.1021/acs.nanolett.4c02571. Epub 2024 Nov 6.
Magnetic tunnel junctions (MTJs) with ultrathin MgO tunnel barriers are at the heart of magnetic random-access memory (MRAM) and exhibit potential for spin caloritronics applications due to the tunnel magneto-Seebeck effect. However, the high programming current in MRAM can cause substantial heating which degrades the endurance and reliability of MTJs. Here, we report the thermal characterization of ultrathin CoFeB/MgO multilayers with total thicknesses of 4.4, 8.8, 22, and 44 nm, and with varying MgO thicknesses (1.0, 1.3, and 1.6 nm). Through time-domain thermoreflectance (TDTR) measurements and thermal modeling, we extract the intrinsic (∼3.6 W m K) and effective (∼0.85 W m K) thermal conductivities of annealed 1.0 nm thick MgO at room temperature. Our study reveals the thermal properties of ultrathin MgO tunnel barriers, especially the role of thermal boundary resistance, and contributes to a more precise thermal analysis of MTJs to improve the design and reliability of MRAM technologies.
具有超薄氧化镁隧道势垒的磁性隧道结（MTJs）是磁性随机存取存储器（MRAM）的核心，并且由于隧道磁塞贝克效应而在自旋热电子学应用中展现出潜力。然而，MRAM中的高编程电流会导致大量发热，从而降低MTJs的耐久性和可靠性。在此，我们报告了总厚度分别为4.4、8.8、22和44纳米且氧化镁厚度不同（1.0、1.3和1.6纳米）的超薄钴铁硼/氧化镁多层膜的热特性。通过时域热反射（TDTR）测量和热建模，我们在室温下提取了1.0纳米厚的退火氧化镁的本征热导率（约3.6 W m K）和有效热导率（约0.85 W m K）。我们的研究揭示了超薄氧化镁隧道势垒的热特性，尤其是热边界电阻的作用，并有助于对MTJs进行更精确的热分析，以改进MRAM技术的设计和可靠性。
