A memory device that can be switched between the normal state and superconducting state by an external magnetic field is proposed. The device consists of a superconducting/double magnetic (SM 1 M 2) trilayer and is switched in a manner analogous to giant magnetoresistive memory devices. Using Usadel equations it is shown that the superconducting transition temperature of the device changes when the magnetic configurations of magnetizations of the two lower layers are switched between parallel and antiparallel. Appropriate design parameters are discussed and the materials issues analyzed.

Single-crystal metals have distinctive properties owing to the absence of grain boundaries and strong anisotropy. Commercial single-crystal metals are usually synthesized by bulk crystal growth or by deposition of thin films onto substrates, and they are expensive and small. We prepared extremely large single-crystal metal foils by “contact-free annealing” from commercial polycrystalline foils. The colossal grain growth (up to 32 square centimeters) is achieved by minimizing contact stresses, resulting in a preferred in-plane and out-of-plane crystal orientation, and is driven by surface energy minimization during the rotation of the crystal lattice followed by “consumption” of neighboring grains. Industrial-scale production of single-crystal metal foils is possible as a result of this discovery.

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Through-chip electrodes with high aspect ratios can offer the shortest interconnection and reduce signal delay. Copper has been selected as that electrode material because of its good compatibility to conventional multilayer interconnection in large-scale integration and back end-of-line processes. In this paper, filling vias with higher aspect ratio, 10 m 2 and 70 m depth, used for through-chip electrodes is reported. Removing overhang at via tops is important to achieve perfect via filling. Upon testing a series of electrodeposition conditions, conformal electrodeposits were obtained. With those conformal electrodeposits, seams and voids always remained at the via center. Perfect via filling was achieved by the pulse reverse plating method and by increasing Janus Green B concentration up to 20 mg/L in the plating bath.

Increasing dissipation-free supercurrent has been the primary issue for practical application of superconducting wires. For magnesium diboride, MgB 2 , carbon is known to be the most effective dopant to enhance high-field properties. However, the critical role of carbon remains elusive, and also low-field critical current density has not been improved. Here, we have undertaken malic acid doping of MgB 2 and find that the microscopic origin for the enhancement of high-field properties is due to boron vacancies and associated stacking faults, as observed by high-resolution transmission electron microscopy and electron energy loss spectroscopy. The carbon from the malic acid almost uniformly encapsulates boron, preventing boron agglomeration and reducing porosity, as observed by three-dimensional X-ray tomography. The critical current density either exceeds or matches that of niobium titanium at 4.2 K. Our findings provide atomic-level insights, which could pave the way to further enhancement of the critical current density of MgB 2 up to the theoretical limit.