Superparamagnetic Tunnel Junctions for Logic Devices

逻辑器件的超顺磁隧道结

• 批准号: 1709845
• 负责人: Sara Majetich
• 金额: $ 36万
• 依托单位: Carnegie-Mellon University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-06-15 至 2020-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1709845&HistoricalAwards=false
• 关键词: Superparamagnetic; Tunnel; Junctions; Logic; Devices

Superparamagnets switch back and forth between two stable states without requiring an external power source, using only thermal energy. This project will investigate the potential for a new type of low power computing using superparamagnets, where the switching frequency can be controlled by a small voltage or current. Nanofabrication techniques will be used to make electrical connections to individual superparamagnets, and then the superparamagnets will be coupled together. To evaluate the potential of this approach for probabilistic computing, logic gates and related devices will be built and tested. for performance and energy efficiency in multiplication and in logic operations. The results will be used to estimate the potential power reduction and processing speed of probabilistic logic gates based on superparamagnetic tunnel junctions. If superparamagnetic tunnel junctions can be optimized for reasonably fast, low power probabilistic computation, the results would have tremendous impact on sensors and hand-held electronic devices, where speed is less critical than battery lifetime. A graduate student will gain experience with nanofabrication and high frequency electronics. Hands-on and web-based demonstrations of logic gates will be developed for high school and middle school students, and both the graduate student and undergraduate researchers will be trained as STEM ambassadors, learning to communicate technical information to a broad audience. The proposed research project will design, fabricate, and test superparamagnetic tunnel junctions that can be controlled by a voltage or current, for use in logic devices for probabilistic computing. Suparamagnetic tunnel junctions will be optimized for large changes in the telegraph signal over relatively small difference in the bias voltage or input current. Different alloys will be investigated to reduce the energy barrier for switching, and therefore the speed of the devices. Hard-wired devices will be fabricated, and the thermal switching rates as a function of bias voltage and input current will be measured using high frequency electronics. Following calibration of the individual superparamagnetic tunnel junctions, they will be coupled together into hybrid circuits and the resulting devices will be tested for use in probabilistic computing. Analog multiplication will involve two independent voltage-controlled superparamagnetic tunnel junctions and a CMOS AND gate. Here the time-average value of the output is predicted to be the product of the time-average values of the input signals. This operation is lower energy with probabilistic computing because it does not require analog-to-digital and digital-to-analog conversion steps. Groups of three interconnected superparamagnetic tunnel junctions will also be investigated as prototype logic gates (AND and OR). The output will be measured as a function of the bias voltages controlling the individual tunnel junctions to optimize the coupling strength between devices necessary for the truth table of the logic gate.

超顺磁体在两种稳定状态之间来回切换，不需要外部电源，只使用热能。这个项目将研究一种使用超顺磁网的新型低功率计算的潜力，其中开关频率可以通过小电压或小电流来控制。纳米制造技术将被用来与单个超顺磁网建立电连接，然后超顺磁网将被耦合在一起。为了评估这种方法用于概率计算的潜力，将建造和测试逻辑门和相关设备。以提高乘法和逻辑运算的性能和能效。该结果将被用于估计基于超顺磁性隧道结的概率逻辑门的潜在功率降低和处理速度。如果超顺磁性隧道结能够针对相当快速、低功耗的概率计算进行优化，结果将对传感器和手持电子设备产生巨大影响，在这些设备中，速度不如电池寿命那么关键。研究生将获得纳米制造和高频电子学方面的经验。将为高中生和中学生开发逻辑门的动手和基于网络的演示，研究生和本科生研究人员将接受STEM大使的培训，学习向广大受众交流技术信息。拟议的研究项目将设计、制造和测试可由电压或电流控制的超顺磁性隧道结，用于概率计算的逻辑设备。超顺磁性隧道结将针对偏置电压或输入电流的相对较小差异下电报信号的较大变化进行优化。将研究不同的合金来降低开关的能垒，从而降低器件的速度。将制造硬连线器件，并将使用高频电子学测量热开关率作为偏置电压和输入电流的函数。在对单独的超顺磁性隧道结进行校准后，它们将被耦合到混合电路中，所产生的设备将被测试用于概率计算。模拟乘法将包括两个独立的压控超顺磁性隧道结和一个与门。这里，输出的时间平均值被预测为输入信号的时间平均值的乘积。由于不需要模-数和数-模转换步骤，因此该运算使用概率计算时能耗较低。三组相互连接的超顺磁性隧道结也将作为原型逻辑门(AND和OR)进行研究。输出将作为控制各个隧道结的偏置电压的函数来测量，以优化逻辑门真值表所需的器件之间的耦合强度。

项目成果

Spin-Orbit-Torque Switching in 20-nm Perpendicular Magnetic Tunnel Junctions

• DOI: 10.1103/physrevapplied.10.024013
• 发表时间: 2018-08
• 期刊: Physical Review Applied
• 影响因子: 4.6
• 作者: M. Bapna;Brad Parks;S. Oberdick;H. Almasi;Weigang Wang;S. Majetich

Current control of time-averaged magnetization in superparamagnetic tunnel junctions

• DOI: 10.1063/1.5012091
• 发表时间: 2017-12-11
• 期刊: APPLIED PHYSICS LETTERS
• 影响因子: 4
• 作者: Bapna, Mukund;Majetich, Sara A.
• 通讯作者: Majetich, Sara A.

Magnetic stray fields in nanoscale magnetic tunnel junctions

• DOI: 10.1088/1361-6463/ab4fbf
• 发表时间: 2020-01-23
• 期刊: JOURNAL OF PHYSICS D-APPLIED PHYSICS
• 影响因子: 3.4
• 作者: Jenkins, Sarah;Meo, Andrea;Evans, Richard F. L.
• 通讯作者: Evans, Richard F. L.

Magnetoresistance Dynamics in Superparamagnetic Co−Fe−B Nanodots

超顺磁 Co-Fe-B 纳米点的磁阻动力学

• DOI: 10.1103/physrevapplied.13.014063
• 发表时间: 2020
• 期刊: Physical Review Applied
• 影响因子: 4.6
• 作者: Parks, Brad;Abdelgawad, Ahmed;Wong, Thomas;Evans, Richard F.L.;Majetich, Sara A.
• 通讯作者: Majetich, Sara A.

The role of faceting and elongation on the magnetic anisotropy of magnetite Fe3O4 nanocrystals

• DOI: 10.1038/s41598-020-58976-7
• 发表时间: 2019-09
• 期刊: Scientific Reports
• 影响因子: 4.6
• 作者: R. Moreno;S. Poyser;Daniel Meilak;A. Meo;Sarah Jenkins;V. Lazarov;G. Vallejo-Fernandez;S. Majetich;R. Evans