Dual cut-off direct current-tunable microwave low-pass filter on superconducting Nb microstrips with asymmetric nanogrooves
Dual cut-off direct current-tunable microwave low-pass filter on superconducting Nb microstrips with asymmetric nanogrooves
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DOI：
10.1063/1.4917229
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发表时间：
2015-04-06
影响因子：
4
通讯作者：
Huth, Michael
中科院分区：
文献类型：
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作者：
Dobrovolskiy, Oleksandr V.;Huth, Michael
我们在具有单轴不对称纳米凹槽的超导铌微带上提出了一种双截止、直流可调低通微波滤波器。在不同温度、磁场和直流值下，在 300 KHz-14 GHz 范围内测量了器件的频率响应。当阿布里科索夫涡晶格在空间上与下面的洗衣板钉扎景观相匹配时，微波损耗最有效地减少。微带线的正向传输系数 S-21(f) 具有直流可调截止频率 f(d)，由于钉扎景观的两种不同的斜率陡度，该频率在直流偏置反转时会显着变化。该装置的工作原理依赖于从当涡流在凹槽上被驱动时涡流在低频下的弱耗散响应到当涡流在一个凹槽内振荡时在高频下的强耗散响应的交叉。滤波器的截止频率是可通过直流偏置调节的涡流脱钉频率，因为它减少了纳米图案引起的钉扎效应。报告的结果揭示了具有不对称（棘轮）钉扎景观的超导薄膜的先进微波功能，并且与调节超导平面传输线中的微波损耗相关。 (C) 2015 AIP 出版有限责任公司。
We present a dual cut-off, dc-tunable low-pass microwave filter on a superconducting Nb microstrip with uniaxial asymmetric nanogrooves. The frequency response of the device was measured in the range 300 KHz-14 GHz at different temperatures, magnetic fields, and dc values. The microwave loss is most effectively reduced when the Abrikosov vortex lattice spatially matches the underlying washboard pinning landscape. The forward transmission coefficient S-21(f) of the microstrip has a dc-tunable cut-off frequency f(d) which notably changes under dc bias reversal, due to the two different slope steepnesses of the pinning landscape. The device's operation principle relies upon a crossover from the weakly dissipative response of vortices at low frequencies when they are driven over the grooves, to the strongly dissipative response at high frequencies when the vortices are oscillating within one groove. The filter's cut-off frequency is the vortex depinning frequency tunable by the dc bias as it diminishes the pinning effect induced by the nanopattern. The reported results unveil an advanced microwave functionality of superconducting films with asymmetric (ratchet) pinning landscapes and are relevant for tuning the microwave loss in superconducting planar transmission lines. (C) 2015 AIP Publishing LLC.