Field-free superconducting diode effect in noncentrosymmetric superconductor/ferromagnet multilayers
Field-free superconducting diode effect in noncentrosymmetric superconductor/ferromagnet multilayers
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DOI：
10.1038/s41565-022-01159-4
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发表时间：
2022-06-30
影响因子：
38.3
通讯作者：
Ono, Teruo
中科院分区：
文献类型：
--
作者：
Narita, Hideki;Ishizuka, Jun;Ono, Teruo
二极管效应是电子设备的基础，广泛用于整流器和交流。直流转换器。然而，在低温下，常规半导体二极管具有高电阻率，这在操作期间产生能量损耗和加热。超导二极管效应（英语：Superconducting diode effect）（1-8）依赖于超导体中的反转对称性破缺，可能会缓解这种障碍：在一个方向上，零电阻的超电流可以流过二极管，但对于电流的相反方向，器件进入正常状态，具有欧姆电阻。磁场的应用可以在具有极性结构的Nb/V/Ta超晶格（1，2）中、在具有钉扎中心的不对称图案的超导器件（9）中或在具有感应涡旋的超导体/铁磁体混合器件（10，11）中感应双极。对外部磁场的需要限制了它们的实际应用。最近，在NbSe 2/Nb 3Br 3/NbSe 2结中观察到了无场双折射;它源于由Nb 3Br 8势垒和相关的NbSe 2/Nb 3Br 8界面诱导的非对称约瑟夫森隧道效应（12）。在这里，我们提出了使用非中心对称[Nb/V/Co/V/Ta]（20）多层膜的零场双折射的另一种实现。磁性层提供了必要的对称性破缺，我们可以通过调整结构参数（如组成元素、薄膜厚度、堆叠顺序和重复次数）来调整磁性层。我们通过铁磁层的磁化方向来控制磁层的极性。诸如在本工作中使用的牺牲堆叠结构（13-18）是特别感兴趣的，因为它们与微制造技术兼容并且可以与诸如约瑟夫森结（19-22）的器件集成。因此，本工作中提出的无能量损失的SDES可以实现具有超低功耗的新型非易失性存储器和逻辑电路。
The diode effect is fundamental to electronic devices and is widely used in rectifiers and a.c.-d.c. converters. At low temperatures, however, conventional semiconductor diodes possess a high resistivity, which yields energy loss and heating during operation. The superconducting diode effect (SDE)(1-8), which relies on broken inversion symmetry in a superconductor, may mitigate this obstacle: in one direction, a zero-resistance super-current can flow through the diode, but for the opposite direction of current flow, the device enters the normal state with ohmic resistance. The application of a magnetic field can induce SDE in Nb/V/Ta superlattices with a polar structure(1,2) , in superconducting devices with asymmetric patterning of pinning centres(9) or in superconductor/ferromagnet hybrid devices with induced vortices(10,11). The need for an external magnetic field limits their practical application. Recently, a field-free SDE was observed in a NbSe2/Nb3Br3/ NbSe2 junction; it originates from asymmetric Josephson tunnelling that is induced by the Nb3Br8 barrier and the associated NbSe2/Nb3Br8 interfaces(12). Here, we present another implementation of zero-field SDE using noncentrosymmetric [Nb/V/Co/V/Ta](20) multilayers. The magnetic layers provide the necessary symmetry breaking, and we can tune the SDE by adjusting the structural parameters, such as the constituent elements, film thickness, stacking order and number of repetitions. We control the polarity of the SDE through the magnetization direction of the ferromagnetic layers. Artificially stacked structures(13-18) , such as the one used in this work, are of particular interest as they are compatible with microfabrication techniques and can be integrated with devices such as Josephson junctions(19-22) . Energy-loss-free SDEs as presented in this work may therefore enable novel non-volatile memories and logic circuits with ultralow power consumption.