Results for “Bi2Sr2CaCu2O8+X”

DOE OSTI2024

Modeling of Bi-2212 strand and Rutherford cable in a dipole coil insert

The U.S. Magnet Development Program (US-MDP) explores high-field accelerator magnets compatible with op- erational conditions beyond the limits of Nb3Sn technology. The ongoing R&D High-Temperature Superconductors (HTS) suggests using Bi2Sr2CaCu2O8−x (Bi-2212) as superconducting element. Bi-2212 Rutherford cables maintain a high critical current (IC ) when exposed to a large external magnetic field. However, Bi-2122 exhibits an oversensitive stress-strain response when subject to large Lorentz forces. This paper reports on the magnetic and mechanical analysis of the Bi-2212 cosine-theta insert being developed at Fermilab for a hybrid magnet composed of 2 external layers of Nb3Sn and 2 internal layers of Bi-2212. We performed a FEM analysis of the insert to estimate the HTS stress state in the coil s strands under magnetic and mechanical loads.

D'Agliano, A.↗

DOE OSTI2025

Quantifying Twist Angles in Cuprate Heterostructures with Anisotropic Raman Signatures

Artificially engineered twisted van der Waals (vdW) heterostructures have unlocked new pathways for exploring emergent quantum phenomena and strongly correlated electronic states. Many of these phenomena are highly sensitive to the twist angle, which can be deliberately tuned to tailor the interlayer interactions. This makes the twist angle a critical tunable parameter, emphasizing the need for precise control and accurate characterization during device fabrication. In particular, twisted cuprate heterostructures based on Bi 2 Sr 2 CaCu 2 O 8 + x (BSCCO) have demonstrated angle-dependent superconducting properties, positioning the twist angle as a key tunable parameter. However, the twisted interface is highly unstable under ambient conditions and vulnerable to damage from conventional characterization tools such as electron microscopy or scanning probe techniques. In this work, a fully non-invasive, polarization-resolved Raman spectroscopy approach is introduced for determining twist angles in artificially stacked BSCCO heterostructures. By analyzing twist-dependent anisotropic vibrational Raman modes, particularly utilizing the out-of-plane A 1g vibrational mode of Bi/Sr at ≈116 cm −1 , clear optical fingerprints of the rotational misalignment between cuprate layers are identified. The high-resolution confocal Raman setup, equipped with polarization control and RayShield filtering down to 10 cm −1 , allows for reliable and reproducible measurements without compromising the material's structural integrity.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗