Superparamagnetic Tunnel Junctions for Logic Devices

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。该项目将研究使用超顺磁体的新型低功耗计算的潜力，其中开关频率可以由小电压或电流控制。纳米制造技术将用于将单个超顺磁体进行电连接，然后将超顺磁体耦合在一起。为了评估这种方法在概率计算中的潜力，逻辑门和相关设备将被构建和测试。在乘法和逻辑运算中的性能和能量效率。研究结果将用于估计基于超顺磁隧道结的概率逻辑门的潜在功耗降低和处理速度。如果超顺磁隧道结可以优化为合理快速、低功耗的概率计算，那么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，速度不如电池寿命重要。研究生将获得纳米制造和高频电子学方面的经验。将为高中和初中学生开发逻辑门的实践和基于网络的演示，研究生和本科生的研究人员将被培训为STEM大使，学习向广泛的受众传达技术信息。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隧道结，用于概率计算的逻辑设备。超顺磁隧道结将在相对较小的偏置电压或输入电流差异上对电报信号的大变化进行优化。研究人员将研究不同的合金，以减少开关的能量垒，从而降低器件的速度。硬连线器件将被制造出来，热开关率作为偏置电压和输入电流的函数将使用高频电子测量。在对单个超顺磁隧道结进行校准后，它们将被耦合到混合电路中，所得到的设备将被测试用于概率计算。模拟倍增将涉及两个独立的压控超顺磁隧道结和一个CMOS与门。在这里，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。该操作使用概率计算能耗较低，因为它不需要模数和数模转换步骤。三组相互连接的超顺磁隧道结也将作为原型逻辑门（与或）进行研究。输出将作为控制单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。

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.