A team of scientists from the University of Groningen, along with international collaborators, has validated the presence of an elusive superconductive state, termed FFLO, which was first theoretically posited in 2017. By employing a device that uses a double layer of molybdenum disulfide to manipulate this state, they may significantly progress the realm of superconducting electronics.
In an innovative experiment, researchers from the University of Groningen partnered with fellow scholars from universities of Nijmegen and Twente in the Netherlands, and the Harbin Institute of Technology in China. Their collective effort successfully verified the existence of this particular superconductive state that was theoretically proposed in 2017.
The joint study, presenting evidence of the unique form of the FFLO superconductive state, was recently released in the journal Nature. This significant breakthrough holds substantial promise for the field of superconducting electronics.
Professor Dr. Justin Ye, who heads the Device Physics of Complex Materials group at the University of Groningen and is the principal author of the Nature paper on the FFLO superconducting state, has been researching the Ising superconducting state. This special state resists magnetic fields that usually obliterate superconductivity, a phenomenon initially characterized by the team in 2015.
By 2019, they had developed a device featuring a double layer of molybdenum disulfide, which could link the Ising superconductivity states found in both layers. Notably, the device, crafted by Ye and his team, facilitates the toggling of this protective mechanism on or off via an electric field, thereby creating a superconducting transistor.
Their research addresses a long-standing hurdle in superconductivity. In 1964, four scientists (Fulde, Ferrell, Larkin, and Ovchinnikov) hypothesized a unique superconducting state – the FFLO state, which could potentially occur under specific conditions of low temperature and high magnetic field.
In conventional superconductivity, electrons move as Cooper pairs in opposite directions at identical speeds, resulting in a total kinetic momentum of zero. However, the FFLO state introduces a slight speed disparity between the electrons in the Cooper pairs, leading to a net kinetic momentum.
“Claims of this state’s existence in regular superconductors are few and still ambiguous,” Ye notes.
To instigate the FFLO state in a standard superconductor, a substantial magnetic field is essential. Yet, the influence of the magnetic field necessitates careful adjustment. Specifically, the Zeeman effect, required for assigning roles to the magnetic field, differentiates electrons in Cooper pairs based on their spins (a magnetic moment), but disregards the orbital effect, which ordinarily negates superconductivity.
Ye describes the process as a “delicate balance between superconductivity and the external magnetic field.”
Ising superconductivity, a concept introduced and published by Ye and his team in the journal Science in 2015, mitigates the Zeeman effect. Ye explains that “By eliminating the key component that enables conventional FFLO, we’ve made room for the magnetic field to exert its other role – the orbital effect.”
In their recent study, they demonstrate a clear indication of the orbital effect-driven FFLO state in their Ising superconductor. “This is an unconventional FFLO state, first envisioned in theory in 2017,” says Ye.
In conventional superconductors, inducing the FFLO state demands extremely low temperatures and a potent magnetic field. However, with Ye’s Ising superconductor, the state can be achieved with a milder magnetic field and at higher temperatures.
In 2019, Ye first detected signs of an FFLO state in his molybdenum disulfide superconducting device. However, definitive proof was elusive until his Ph.D. student Puhua Wan successfully created samples of the material meeting all criteria to confirm the existence of a finite momentum in the Cooper pairs. Wan is the first author of the Nature paper.
Further exploration of this new superconducting state is necessary. Ye concludes, “There is much to learn about this state. Our future challenge is to uncover how kinetic momentum impacts the physical parameters and how understanding this state could let us manipulate it in devices like transistors.”
Reference: “Orbital Fulde–Ferrell–Larkin–Ovchinnikov state in an Ising superconductor” by Puhua Wan, Oleksandr Zheliuk, Noah F. Q. Yuan, Xiaoli Peng, Le Zhang, Minpeng Liang, Uli Zeitler, Steffen Wiedmann, Nigel E. Hussey, Thomas T. M. Palstra, and Jianting Ye, 24 May 2023, Nature.
DOI: 10.1038/s41586-023-05967-z
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Table of Contents
Frequently Asked Questions (FAQs) about Superconductive State FFLO
What is the superconductive state that has been discovered?
The newly confirmed superconductive state is called the FFLO state. This elusive state was theoretically predicted in 2017 and has now been confirmed by scientists from the University of Groningen and other international collaborators.
Who led the research on the superconductive state?
The research was led by Professor Justin Ye, who heads the Device Physics of Complex Materials group at the University of Groningen.
What makes the FFLO state special in the realm of superconductivity?
In the FFLO state, there is a slight speed difference between the electrons in Cooper pairs, leading to a net kinetic momentum. This contrasts with conventional superconductivity where electrons move as Cooper pairs in opposite directions at identical speeds, resulting in a total kinetic momentum of zero.
How does this discovery impact the field of superconducting electronics?
The verification of the FFLO state’s existence could significantly advance the field of superconducting electronics. By understanding and potentially controlling this state, we might see new developments in devices such as transistors.
What materials and methods were used in this research?
The researchers developed a device featuring a double layer of molybdenum disulfide. This device could link the Ising superconductivity states found in both layers and allowed the researchers to toggle a protective mechanism on or off using an electric field.
5 comments
OMG! I studied about FFLO state in my grad school, never thought I’d see the day they’d actually confirm its existence… Science rocks!
Proud to see such great work coming out of the University of Groningen. Keep pushing the boundaries, folks. The sky’s the limit!
So it took them over 4 years to confirm the FFLO state after it was predicted. Just shows how complex this science thing is… mind-boggling…
So, we’re messing with electrons in Cooper pairs now, huh? Wonder what’s next. Teleportation? Time travel?
Wow! This is pretty cool, aint it? Superconductors n stuff sounds like something straight outta a sci-fi movie, but its real!