21 February 2019
What makes iron-based superconductors tick
Published online 10 December 2015
Scientists illuminate the microscopic phenomena that trigger superconductivity in iron selenide crystals.
Researchers have discovered how angular momentum or spin fluctuations of iron atoms along with a symmetry-tweaking electronic phase known as nematicity are linked to superconductivity in iron selenide superconductors1.
This discovery means iron selenide superconductors can be manipulated for use in future electronic gadgets.
Previous theoretical studies suggested that spin fluctuations could drive superconductivity and nematicity. But the link between the three had not been well established experimentally in iron-selenide-based superconductors until this study.
Using neutron scattering measurements, the research team, including researchers from Fudan University, China, and Fayoum University, Egypt, probed the link in iron selenide crystals over a wide range of momentum and energy.
The scientists observed that the crystals exhibited superconductivity at up to 8.7 K. In this temperature range, they found that spin fluctuations were closely related to superconductivity.
The spin fluctuations enhanced abruptly below nematic phase transition temperature at 90 K when the structure of the crystals changed from orthorhombic to tetragonal, the researchers say.
“This research supports the theoretical proposals that spin fluctuations drive nematicity and superconductivity, and is critical in identifying the microscopic mechanism behind superconductivity in iron-selenide-based materials,” says lead researcher Jun Zhao.
- Wang, Q. et al. Strong interplay between stripe spin fluctuations, nematicity and superconductivity in FeSe. Nat. Mater. http://dx.doi.org/10.1038/NMAT4492 (2015).